TSTCK 
LiBRART 


THE   FUNDAMENTALS 
OF   PSYCHOLOGY 


BY 


W.   B.    PILLSBURY 

PROFESSOR   OF   PSYCHOLOGY,    DIRECTOR   OF   THE 
PSYCHOLOGICAL   LABORATORY,   UNI- 
VERSITY  OF   MICHIGAN 


THE   MACMILLAN   COMPANY 
1916 

All  rights  reserved 


■^F 


-D 


^^ 


EDUC. 

PSYCH. 

LIBRARY 


Copyright,  1916, 
Bv  THE  MACMILLAN  COMPANY. 

Setupandelectrotyped.     Published  August,  19x6      ReDrinted 
September,  October.  November,  1916.  *      '    ^  °-     ^epnnted 


Nortaooti  iDffBB 

J.  S.  Cuahing  Co.  -  Berwick  4  Smith  Co. 

Norwood,  Mass..  U.S.A. 


PREFACE 

This  book  is  intended  to  fill  a  gap  which  exists  to-day 
between  the  smaller  texts  and  the  reference  hand-books. 
I  have  had  in  mind  the  needs  of  one  of  my  own  classes 
which  devotes  a  year  to  psychology  and  mcludes  stu- 
dents who  have  had  no  previous  work  in  the  subject. 
They  have  more  than  time  to  cover  the  present  texts 
but  are  lost  in  the  details  of  the  larger  works,  particu- 
larly in  connection  with  the  nervous  system,  sensation, 
and  perception. 

I  have  written  for  the  student  primarily  and  have  not 
presupposed  any  preliminary  knowledge.  I  have  par- 
ticularly avoided  reference  to  current  theories  before 
they  are  explained  and  have  indulged  in  no  arguments 
on  controversial  matter  for  the  benefit  of  colleagues 
rather  than  of  the  student.  Opposing  theories  are  dis- 
cussed only  as  they  may  illumine  statements  of  fact  or 
where  they  have  great  historical  importance  and  then 
only  if  the  problem  is  real  but  is  not  settled. 

The  technical  psychologist  may  miss  long  discussions 
of  general  method  and  points  of  view.  I  have  replaced 
them  by  fuller  statements  of  the  results  of  experiment 
and  more  detailed  treatment  of  the  generally  accepted 
body  of  facts.  I  have  drawn  upon  the  work  of  all 
schools  without  reference  to  the  theories  that  the  work- 
ers held,  and  have  stated  the  results  in  terms  that 
«i  r'  >^  v>  r :, 


VI  PREFACE 

seemed  most  suitable  to  the  particular  material.  Sen- 
sation and  perception  are  discussed  in  structural  terms, 
action  of  all  sorts  in  behavioristic  terms.  This  gives 
some  inconsistencies,  but  they  are  preferable  to  the 
awkward  phrases  that  would  result  from  using  the  ter- 
minology of  any  school  to  the  exclusion  of  the  others. 

My  own  theory  incHnes  towards  a  functionalism. 
The  book  is  more  concerned  with  what  consciousness 
does  than  with  what  it  is.  As  opposed  to  the  extreme 
behaviorism,  however,  I  am  not  concerned  alone  with 
understanding  the  movements  of  the  organism  and  the 
function  of  the  movements,  but  also  with  understanding 
knowledge  and  the  way  in  which  it  develops.  It  is 
my  belief  that  the  content  of  the  science  is  the  same 
whatever  the  point  of  view  from  which  the  subject  be 
approached,  and  that  this  content  is  essential  and 
changes  slowly  and  then  through  growth.  The  theories 
are  less  important  and  likely  to  change  from  decade  to 
decade.  In  contrast  with  some  of  the  recent  authors 
I  have  endeavored  to  supply  the  content  and,  while  I 
have  stated  my  own  theories  in  some  detail,  have 
attempted  to  be  sufficiently  undogmatic  to  give  the  in- 
structor opportunity  to  develop  his  own  point  of  view. 

I  take  pleasure  in  acknowledging  the  help  that  has 
been  given  in  the  preparation  of  the  manuscript  by 
Dr.  Adams,  Miss  Perkins,  and  my  wife.  All  have  read 
the  manuscript  or  portions  of  it  and  have  made  numer- 
ous suggestions.  The  latter  has  also  aided  with  proofs 
and  index.  Dr.  Huber  has  aided  much  in  the  selection 
of  illustrations  for  the  neurological  portions,  and  at 
his  suggestion  Mr.  Atwell  of  his  laboratory  has  drawn 
sections  for  Figures  19,  21,  23,  24,  25,  and  26.  I  ex- 
press my  gratitude  to  both. 


PREFACE  VU 

I  also  desire  to  thank  the  individuals  and  publishers 
who  have  permitted  me  to  reproduce  cuts:  Professor 
Jennings  for  cuts  from  his  "  Behavior  of  Lower  Organ- 
isms," Dr.  Barker  for  illustrations  from  his  "  Nervous 
System,"  W.  B.  Saunders  &  Co.  for  figures  from  How- 
ell's "Text-book  of  Physiology"  and  Ruber's  "Histol- 
ogy," to  Rebmann  Bros,  for  cuts  from  Bing's  "  Regional 
Diagnosis,"  and  to  The  Macmillan  Co.  for  cuts  from 
Titchener's  "Text-book  of  Psychology,"  from  Thorn- 
dike's  "Animal  Mind,"  and  Foster's  "Physiology." 

W.   B.  PILLSBURY. 

Ann  Arbor,  Michigan, 
April  25,  1916. 


TABLE    OF    CONTENTS 


I. 
II. 
III. 

IV. 
V. 
VIV 

VII. 

VIII. 

IX. 

X. 

X\.J 
XII. 
XIII. 
XIV. 

XV. 
XVI. 


Introduction 

The  Nervous  System.    Cord  and  Brain  Stem    . 
The  Functions  of  the  Cerebrum 

Sensation  —  Vision 

Sensation -Audition,  Touch,  etc.,  Weber's  Law 

IMAGES  AND  THE  LAWS  OF  CENTRALLY  AROUSED 

Sensations 
Attention  and  Selection 
Perception  —  Space 
Perception  —   Visual     Movement,    Time,    and 

General  Laws  . 
Memory     . 
Reasoning 
Instinct     . 

Feeling  and  Affection 
Emotion  and  Temperament 
The  General  Principles  of  Action  — Will 
The  Self 


PAGE 
I 

15 
65 
98 

216 
238 
267 

322 

345 
387 
420 

443 
467 
496 
530 


FUNDAMENTALS    OF 
PSYCHOLOGY 


CHAPTER  I 
INTRODUCTION 

Just  at  present  there  is  much  dispute  among  psycholo- 
gists over  the  most  satisfactory  method  of  defining  the 
science.  The  difficulty  arises  in  large  part  from  the 
number  of  theories  held  in  the  past  which  still  haunt  the 
domain  of  the  Hving  science  although  no  longer  accepted 
and,  in  many  cases,  entirely  out  of  harmony  with  the 
present  attitude  toward  the  subject.  While  the  formal 
definition  offers  many  difficulties,  it  is  comparatively 
easy  to  state  what  the  science  is  doing  and  the  nature  of 
the  facts  that  it  studies,  fit  deals  with  the  activities 
commonly  known  as  mental,  the  processes  of  perceiving, 
of  remembering,  of  thinking,  and  particularly  with  the 
acts  of  the  individual.  As  in  any  other  science,  its  aim 
is  first  to  determine  what  these  activities  are,  what  they 
do,  and  then  to  trace  them  to  their  conditions,  to  under- 
stand them  in  the  light  of  every  fact  that  can  have  any 
bearing  upon  them.  )  It  is  easier  to  show  what  psychol- 
ogy is  and  what  ifs  aims  are  by  concrete  illustration 
than  by  abstract  statements. 

Take  memory,  for  example.     Psychology  is  concerned 


2  FUNDAMENTALS  OF  PSYCHOLOGY 

with  knowing  all  that  is  possible  of  how  we  learn  and 
remember.     Every  one  is  famihar  with  memory  in  a 
purely  objective  way.     A  lesson  is  studied  and,  when 
occasion  arises,  much  of  it  can  be  repeated.     How  one 
remembers  troubles  the  ordinary  individual  very  little. 
When  questioned  he  knows  almost  as  little  of  how  he 
remembers  as  does  the  questioner.     The  task  of  psychol- 
ogy is  to  discover  the  laws  and  conditions  of  learning  and 
recall  in  all  of  their  details.     It  must  know  what  methods 
lead  most  certainly  and  quickly  to  a  first  learning,  what 
kind  of  learning  will  permit  retention  for  the  longest 
time,  and  how  forgetting  takes  place.     These  investiga- 
tions have  been  carried  out  in  great  detail,  as  will  be  seen 
in  a  later  chapter.    While  memory  itself  is  regarded  as 
a  mental  process,  the  measurements  of  memory  are  as 
objective  as  are  measurements  of  the  strength  of  materials, 
although  of  course  the  variation  is  greater  from  measure- 
ment to  measurement.     The  experiments  require  some- 
what complicated  special  apparatus  and  a  special  train- 
ing in  manipulation,  and  the  methods  used  and  the 
results  obtained  may  be  stated  in  terms  thai  make  n 
mention  of  mind.     Thus,  the  most  satisfactory  rate  '^ 
retention,  the  best  method  of  distributing  the  ^epet  'i^  ; 
the  rate  of  forgetting,  are  determined  by  obj«(  uw    i.     - 
that  hold  irrespective  of  theory.     It  is  also  possibi' 
study  very  many  of  the  conditions  of  recall  b     >^^ 
methods.     One  may  speak  a  word  and  ask  tt 
to  speak  the  first  word  that  occurs  to  him.     . «  study  oi 
these  words  and  of  their  connections  permits  a       ' 
in  a  perfectly  objective  way  of  the  laws  that 
recall.    These  are  the  facts  with  which  psycho- 


INTRODUCTION  3 

deal.  They  may  be  collected  in  much  the  same  way  for 
each  of  the  different  acti\dties  of  man. 

This- purely  objective  and  experimental  study  of  mental 
activities  is  observation.  It  may  be  carried  on  for  man 
in  exactly  the  same  way  as  for  animals,  by  making  experi- 
ments from  the  outside,  with  no  attempt  to  discover 
directly  what  has  been  going  on  within  the  individual. 
But  this  is  not  the  only  method  of  psychology.  We  may 
also  make  use  of  the  individual's  report  on  the  processes. 
He  can  observe  from  within  what  accompanies  and  pre- 
cedes the  activities  objectively  measured.  This,  the 
process  of  self-observation  or  introspection,  will  in  many 
cases  supplement  the  results  of  direct  observation,  and 
the  individual  who  is  experimented  upon  can  often  notice 
occasions  for  expressions  that  are  not  given  in  the  state- 
ments themselves.  While  the  fundamental  causes  of 
most  mental  phenomena  are  as  much  hidden  from  him  as 
from  the  experimenter,  he  can  add  an  account  of  accom- 
panying phenomena  that  is  nearly  always  suggestive, 
and  may  at  times  furnish  a  solution  for  the  questions 
raised  by  the  objective  results.  The  two  methods  of 
psychology,  then,  are  observation  and  introspection. 
One  gives  the  phenomena  as  they  present  themselves  to 
the  onlooker,  the  other  as  they  appear  to  the  individual 
investigated.  At  present  both  methods  are  used  under 
experimental  conditions  that  make  it  possible  to  control 
the  stimuli  and  to  provide  means  of  measuring  many 
reactions  that  would  escape  either  unaided  observation 
or  introspection. 

While  practically  all  are  agreed  as  to  what  psychology 
is  to  study  and  on  most  of  the  results  obtained,  there  is 


4  FUNDAMENTALS   OF   PSYCHOLOGY 

and  always  has  been  much  controversy  over  what  it  is 
that  is  studied.  Three  definitions  are  current  at  present 
which  differ  in  the  statement  of  the  object  to  be  studied. 
The  first  asserts  that  psychology  is  the  science  of  mind,  a 
direct  translation  of  the  original  Greek.  Two  meanings 
are  given  to  the  word  mind.  One  regards  it  as  something 
substantial,  an  actual  thing  or  an  actual  force  which 
produces  certain  effects  or  manifests  itself  in  the  phe- 
nomena we  directly  experience ;  the  other,  of  more  recent 
development,  asserts  that  mind  is  just  these  manifesta- 
tions, the  sum  of  mental  states  without  any  assumption 
as  to  what  it  is  that  produces  them.  A  second  definition 
defines  niind\as  the  science  of  consciousness.  Conscious- 
ness, like  mind  in  its  second  definition,  is  just  the  series 
of  mental  phenomena,  the  memories,  thoughts,  percep- 
tions, emotions  and  feeHng  as  they  are  immediately 
experienced.  A  tlurd  definition,  most  recent  of  all, 
defines  psychology  as  the  science  of  behavior.  By  be- 
havior is  meant  the  activity  of  the  man  or  animal  as  it 
can  be  observed  from  the  outside,  either  with  or  without 
attempting  to  determine  the  mental  states  by  inference 
from  these  acts. 

The  various  definitions  can  be  illustrated  concretely 
in  the  memory  process.  As  theory  of  mind,  psychology 
regards  memory  as  one  of  the  manifestations  of  mind 
and  either  is  concerned  with  understanding  mind  through 
this  manifestation  or  is  content  to  describe  remembering 
as  one  of  the  mental  capacities.  In  fact,  earlier  theories 
of  memory  were  content  to  assert  that  ideas  were  stored 
in  rriind  vi   I'lal  i.licy    wcie  ui'  luaac  upon  a 

waxen  plate.     In  either  case',  n(^  -ould  be  ^iveti 


INTRODUCTION  5 

as  to  how  they  were  stored  or  how  they  might  be  rein- 
stated. Mind  was  both  an  active  agent  and  a  receptacle, 
the  sole  means  of  accounting  for  mental  states.  If 
mind  is  to  be  defined  as  the  sum-total  of  mental  states  in 
accord  with  the  more  recent  suggestions,  it  is  practically 
synonymous  with  consciousness,  —  the  first  definition 
merges  into  the  second.  As  the  science  of  consciousness, 
psychology  is  concerned  with  a  description  of  the  different 
memory  images,  with  the  detefmination  of  the  order  of 
their  appearance  and  with  all  else  that  is  related  to  their 
structure  and  function.  It  takes  into  consideration  noth- 
ing that  is  not  to  be  discovered  by  the  individual  who 
remembers.  It  excludes  consideration  of  mind  as  a 
storehouse,  for  that  is  not  open  to  observation ;  and  also 
of  the  wax  plate  and  all  similar  entities.  All  that  it  can 
do  is  to  determine  the  laws  of  succession  of  the  mental 
states,  and  to  describe  the  mental  states  themselves. 
As  science  of  behavior,  psychology  only  need  investigate 
the  capacity  of  the  individual  to  remember.  The  indi- 
jvidual  is  asked  to  repeat  words  or  syllables  a  certain  num- 
ber of  times  under  different  conditions.  After  a  certain 
period  or  certain  periods  he  is  tested  to  see  how  many  he 
■remembers.     From  these  results  laws  can  be  formulated 

for  the  mxost  effective  means  of  learning. 
The  second  and  third  of  these  definitions  are  alike  in 
that  neither  implies  any  theories  concerning  what  can- 
n  ot  be  seen,  what  is  not  open  to  observation.     Each 
would  content  itself  with  observation  from  within  or  from 
'/  thout  of  what  actually  takes  place.     As  in  any  science, 
h  form  of  observation  may  be  subjected  to  experiment, 
:onditions  of  learning  may  be  varied  at  will,  the  cor- 


FUNDAMENTALS    OF   PSYCHOLO( 


of  behavior 
s  tends  t  > 


responding  changes  in  results  noted  and      rmulated  ii 
laws.     The  choice  between  them  must  be  :  *"  ^    • 

of  the  methods  that  each  emphasizes,  anc 
of  the  accuracy  with  which  each  can  be  i 
the  facts  that  are  to  be  included  under  ps 

strict  definition,  all  is  at  once  consciousness     .     . . . .  ■ 

for  most  individuals.     Few  would  deny  tha     11  beha\''»  n 

to  be  known,  must  become  conscious,  eithe 

or  observer;  and  none  would  deny  that  < 

unless  it  is  to  remain  forever  individual, 

itself  in  behavior.     The  choice  of  scienc< 

turns,  first,  upon  the  fact  that  conscious] 

imply  something  removed  from  observatic 

mystical,  a  thing,  rather  than  a  series   of 

secondly,  upon  the  fact  that  behavior  is  th 

sive  term;    and  finally,  upon  the  doubt 

recent  writers  as  to  whether  consciousness  t 

exists  for  them  individually.     It  emphasizes 

laws  of  action  must  first  be  discovered,  and 

and  theoretical  explanations  must  be  deri 

actual  results  of  experiment  and  observatioi 

be  accepted  in  advance. 

The  real  quarrel  between  definitions  li 
what  the  phenomena  of  consciousness  are, 
general  laws  that  express  them,  but  in  the 
explanation.  Thus  the  exponent  of  the 
haviorist  view  differs  from  the  extreme  sul 
in  the  facts  he  accepts  but  in  that  he  doe 
that  consciousness  exists,  or  if  it  exists,  that 
important  part  in  controlling  action.  For 
tivist,  on  the  other  hand,  consciousness  sec 


i  theoiK- 


not  ar 

I    ;i.s   f-r 


INTRODUCTION  7 

term  by  which  all  else  must  be  explained ;  behavior  is 
secondary.  In  the  first  definition,  the  use  of  mind  is 
very  ob\dously  the  introduction  of  a  theoretical  explana- 
tion. No  one  claims  that  it  is  ever  open  to  direct  obser- 
vation, however  important  it  may  appear  to  the  indi- 
viduals that  believe  in  it.  These  differences  of  opinion 
on  theoretical  points  may  very  well  be  neglected  in  the 
development  of  a  description  of  the  mental  life.  After 
facts  have  been  collected  and  laws  formulated,  the  funda- 
mental problems  may  be  attacked  in  the  light  of  those 
results.  Laws  are  bound  to  suggest  wider  generaliza- 
tions, and  these  in  turn  fundamental  causes  or  conditions. 
Ob\dously,  if  we  are  to  define  psychology  as  the  science 
of  beha\-ior,  we  must  Hmit  its  appHcation,  since  all  of 
the  biological  and  even  the  chemical  and  physical  sciences 
are  needed  to  explain  behaiior  in  its  completeness.  In 
practice,  we  limit  ourselves  to  the  explanation  of  intelli- 
gent behavior.  Roughly,  behavior  may  be  regarded  as 
intelligent  when  it  is  modified  by  the  earHer  experience 
of  the  organism.  All  the  acts  of  certain  of  the  lowest 
organisms  and  some  of  the  acts  of  the  highest  are  to  be 
explained  altogether  in  terms  of  the  physical  stimuli  and 
\pi  the  constitution  of  the  organism.  In  consequence, 
[these  responses  are  relatively  invariable,  —  the  organism 
makes  the  same  movements  under  the  same  conditions. 
These  do  not  concern  psychology.  When  behavior  is 
modified,  not  merely  by  the  physical  stimuli  and  chance 
chemical  conditions  of  the  organism,  but  also  by  the 
results  of  earlier  beha\T[or,  we  have  the  first  beginnings 
of  intelligence,  and  the  organism  offers  material  for 
psychology.     Even  in  the  highest  organisms,  psychology 


8 


FUNDAMENTALS    OF   PSYCHOLOGY 


is  concerned  only  with  the  phases  of  beh    -ior  whi  1 

cannot  be  referred  directly  to   chemical   i 

changes  within  and  without  the  organism. 

general  with  the  acts  of  the  organism  as  a  v\ 

than  of  the  parts,  and  it  considers  the  acts       ... 

plains  only  in  so  far  as  they  are  not  explainc     by  ph> 

ology  and  other  distinctly  biological  sciences.     In  gene^i 

again,  psychology  treats  the  beha^dor  in  sp  i.ir  ar.  it 

determined  by  previous  acts  of  the  individ 

action  of  more  remote  influences,  while  the  ot 

treat  the  same  behavior  in  so  far  as  it  is  due  t 

ties  of  particular  organs  and  to  the  more  inechaiiu . 

forces. 

Psychology  in  its  Relation  to  Other  Science  ^ . ; 

of  all  behavior  is  to  be  explained  by  other     lences,  b;. 
physiology,  by  anatomy  and  the  other  biologi-  il  spencer 
the  psychologist  must  take  the  results  of  th     • 
into  consideration.     He  must  know  what  i 
problem  they  solve  and  what  they  leave  o^ 
to  discuss.     He  must  also  use  many  of  thei      - 
attaining  his  own  conclusions.     Knowledge  o 
ture  and  function  of  the  nervous  system  is  ]  .  •  > 

important,  as  in  the  higher  organisms  pract:    lily  all  oi 
behavior  is  an  expression  of  nervous  action.     '^:\^- 
for  the  more  complex  forms  of  behavior  de  - 
the  nervous  system,  and  defects  in  the  nerv 
are  closely  correlated  with  deviations  from  .il 

behavior.     Consciousness,  too,  is  closely  rcl;  :»e 

nervous  system.     One  can  become  aware  '.  n-d 

objects  only  as  stimuli  are  carried  to  the  bi 
sensory   nerves;    memory   defects   accompa  .  s 


INTRODUCTION  9 

to  definite  portions  of  the  brain  tissue.  In  fact,  we  have 
every  reason  to  believe  that  all  forms  of  consciousness 
have  definite  accompaniments  in  the  nervous  system. 
Viewed  from  any  standpoint,  the  problems  of  psychology 
are  closely  bound  up  with  the  problems  of  the  nervous 
system.  A  knowledge  of  nervous  anatomy  and  physi- 
ology is  essential  to  an  understanding  of  either  con- 
sciousness or  behavior.'  We  shall  begin  our  work  with  a 
brief  survey  of  the  more  important  facts  of  neurology. 
This  survey,  it  may  be  well  to  state,  is  not  part  of  the 
field  of  psychology.  It  is  given  here  only  because  one 
cannot  presuppose  the  knowledge  on  the  part  of  all 
readers,  and  the  facts  are  necessary  to  an  understanding 
of  many  definitely  psychological  problems.  A  full  knowl- 
edge involves  also  the  results  of  physics  and  chemistry. 
All  of  the  activities  of  the  organism  involve  chemical 
processes,  and  the  stimuH  to  action  are  physical.  In 
brief,  all  of  the  sciences  dealing  with  any  of  the  forces  that 
arouse  or  modify  action  and  with  the  nature  of  the 
organism,  itself  must  be  of  assistance  to  psychology. 

In  addition  to  the  sciences  to  which  psychology  must 
look  for  aid  in  sohdng  its  problems,  it  also  has  close  rela- 
tions with  many  of  the  social  sciences,  which  either  depend 
upon  it  or  share  with  it  in  the  solution  of  their  own 
problems.  Sociology  in  its  attempt  to  understand  society 
must  take  into  consideration  the  individuals  of  which  it  is 
composed,  and  welcomes  whatever  knowledge  psychology 
can  give  on  the  subject.  In  many  of  its  phases  sociology 
is  social  psychology.  Similarly,  much  of  the  work  in 
economics  depends  upon  a  knowledge  of  mental  laws. 
The  economist,  however,  has  for  the  most  part  developed 


lO  FUNDAMENTALS   OF   PSYCHOLOGY 

his  laws  of  human  nature  for  himself  from  a  study  of 
practical  relationships,  rather  than  taken  them  from 
psychology.  The  relationship  of  psychology  to  phi- 
losophy is,  for  the  theoretical  problems,  closest  of  all. 
Psychology  was  the  latest  of  the  sciences  to  separate 
from  philosophy,  and  the  attitude  toward  many  of  the 
fundamental  problems  is  still  profoundly  influenced  by 
philosophical  considerations.  Each  of  the  definitions  of 
psychology  discussed  has  developed  in  response  to  philo- 
sophical theories.  On  the  other  hand,  many  of  the 
philosophical  discussions  presuppose  a  knowledge  of 
psychology.  There  has  always  been  an  interaction 
between  the  two  disciplines. 

The  Varieties  of  Psychology.  —  The  more  usual  classi- 
fications of  psychology  have  been  based  upon  the  ways 
of  approaching  the  subject,  upon  the  methods  used  in  the 
investigation,  or  upon  the  field  that  is  treated.  The 
older  psychologies  were  divided  into  rational  or  deduc- 
tive, and  empirical  or  inductive  (on  the  basis  of  the 
fundamental  method  employed).  Recently  all  psychol- 
ogy has  tended  to  become  empirical  or  inductive,  par- 
ticularly with  the  increased  use  of  experiment ;  and  the 
method  of  deduction  has  been  applied  only  to  topics 
that  do  not  lend  themselves  to  experiment  or  observa- 
tion. Rational  psychology  as  a  separate  field  has  largely 
disappeared.  Even  Wolff,  who  may  have  been  said  to 
i,^,,^  :^4^^r^A^^nc.A  r»r  Qf  lpqc;t  to  ha vp made  laree  use  of  the 


irom 


INTRODUCTION  II 

physics.  The  former  treats  of  the  mental  processes  in 
their  relation  to  the  nervous  system  and  its  action.  It  is 
implied  in  all  forms  of  psychology  at  the  present  time 
and  differs  from  the  others  for  the  most  part  only  in  the 
relative  amount  of  space  devoted  to  the  physiological 
aspects.  All  psychologists  at  present  presuppose  a 
knowledge  of  the  nervous  system  and  its  action,  even  if 
they  do  not  discuss  it  explicitly.  Much  the  same  may 
be  said  of  psycho-physics.  This  lays  greatest  emphasis 
upon  the  part  the  physical  stimuH  play  in  mental  pro- 
cesses, and  the  way  in  which  mental  states  change 
with  changes  in  physical  stimuli.  Both  physiological 
psychology-  and  psycho-physics  were  taken  from  famous 
works  on  psychology,  the  one  by  Wundt,  the  other  by 
Fechner.  Closely  connected  with  the  physiological 
psychology  is  objective  psycholog}',  a  name  given  to 
several  recent  books.  This  not  merely  places  the  em- 
phasis upon  the  nervous  system  and  its  activity,  but  also 
does  not  take  consciousness  into  consideration  at  all. 
It  studies  beha\dor  altogether  from  the  outside. 

Different  Fields  of  Psychology.  —  Psychology  may  be 
di\dded  along  the  lines  of  subject  matter.  Most  psychol- 
ogy- deals  with  the  adult  human  individual,  but  recently 
many  additional  and  special  fields  have  been  developed. 
Society,  or  man  in  the  mass,  may  be  studied  as  well  as  the 
indi\ddual.  A  society  shows  many  characteristics  dif- 
ferent from  and  added  to  the  quahties  of  the  individual. 
A  mob,  e.g.,  will  do  many  things  that  few  if  any  of  the 
indi\-iduals  who  compose  the  mob  would  countenance 
in  calm  moments.  These  and  other  phases  of  group 
psychology  have  been  studied  and  a  series  of  important 


12         FUNDAMENTALS  OF  PSYCHOLOGY 

laws  developed.  Race  psychology  deals  with  the 
broader  mental  differences  between  races  and  is  a 
natural  extension  of  social  psychology  but  has  been 
less  fully  developed. 

A  second  group  of  divisions  of  psychology,  genetic 
psychology,  treats  the  less  developed  types,  either  with  the 
object  of  throwing  Kght  upon  the  more  complex  human 
behavior  or  for  their  own  sake.  The  most  fully  devel- 
oped of  these  is  animal  psychology.  The  question 
as  to  whether  animals  are  intelHgent  and  how  their 
inteUigence  compares  with  man's  has  always  interested 
students,  but  until  within  the  last  two  decades  most  of 
the  conclusions  were  based  upon  anecdotes  or,  at  most, 
upon  the  chance  observations  of  travellers  and  natu- 
rahsts.  These  were  obviously  open  to  suspicion.  More 
recently,  experiments  upon  animals  have  been  carried 
on  both  by  biologists  and  psychologists  with  very  impor- 
tant results.  The  behavior  of  typical  animals  from  the 
protozoa  to  the  apes  has  been  studied  exhaustively. 
Much  Kght  has  been  thrown  upon  their  own  activities 
and  many  points  in  human  psychology  have  also  been 
illuminated  by  their  results.  The  development  of  the 
individual  has  also  been  investigated.  Child  study  has 
offered  a  number  of  conclusions  that  make  easier  an 
understanding  of  the  compHcated  activities  of  man. 
The  earHest  years  and  the  period  of  adolescence  have 
received  most  attention. 

Still  another  important  series  of  problems  has  arisen 
in  connection  with  different  forms  of  mental  deteriora- 
tion, the  psychology  of  the  abnormal,  or  pathological 
psychology.     The  relation  of  these  studies  to  normal 


INTRODUCTION 


13 


psychology  has  been  twofold.  They  have  greatly  aided 
in  an  understanding  of  the  normal.  One  is  very  much 
more  certain  that  a  voluntary  act  depends  upon  certain 
stimuli  or  sensations  when  it  can  be  shown  that  the 
absence  of  that  stimulus  causes  a  defect  in  the  movement. 
Disturbances  of  the  self  have  given  a  more  profound 
knowledge  of  what  that  is  or  is  not  than  centuries  of 
speculation  and  introspection.  SHghter  defects  of  sensa- 
tion, color  blindness  and  partial  deafness,  not  to  mention 
the  impairment  of  memory  and  related  processes,  have 
all  given  valuable  aid  in  the  unravelling  of  psychological 
problems  or  have  substantiated  results  obtained  in  other 
ways.  On  the  other  hand,  psychological  methods  and 
psychological  results  have  been  adapted  to  the  study  of 
the  abnormal  and  defective  minds  with  much  theoretical 
and  practical  benefit.  Certain  standardized  tests  have 
come  into  use  which  make  it  possible  to  determine  within 
fairly  close  Hmits  the  degree  of  intelligence  of  the  indi- 
vidual. These  have  proved  of  value  in  the  schools  in 
selecting  the  children  who  are  unable  to  profit  from  the 
usual  training  and  make  it  possible  to  give  them  special 
instruction.  It  has  been  shown  by  an  examination  of 
criminals  and  paupers  that,  in  a  large  number  of  cases, 
a  mental  defect  is  responsible  for  their  failure  to  fit  into 
society,  and  the  necessity  for  special  care  that  shall 
provide  the  ounce  of  prevention  has  been  emphasized. 
Many  of  the  methods  used  to-day  for  the  diagnosis  of 
insanity  have  also  been  developed  in  psychological 
laboratories  and  much  of  the  treatment  has  been  an 
outgrowth  of  psychological  principles,  an  application 
of  psychological  methods. 


14  FUNDAMENTALS    OF   PSYCHOLOGY 

Our  Problem.  —  In  this  work  we  shall  restrict  our- 
selves to  a  study  of  the  normal  adult  human  individual. 
The  other  branches  of  psychology  will  be  considered 
only  as  their  results  aid  us  in  understanding  this  central 
problem,  and  this  they  do  at  practically  every  point. 
We  shall  use  the  results  of  all  methods,  but  shall  enter 
as  Httle  as  possible  into  the  quarrels  as  to  whether  any 
method  is  theoretically  justifiable.  We  shall  assume 
that  there  is  a  body  of  fact  that  is  indifferent  to  the 
theoretical  discussions.  Thus,  in  connection  with  the 
controversy  now  raging  whether  observation  or  introspec- 
tion is  the  method  in  psychology,  we  shall  remain  neutral 
and  make  use  of  the  contributions  of  each.  After  all, 
the  controversy  concerns  us  only  in  the  form  of  expression 
that  may  be  used  to  state  the  results  rather  than  in  the 
validity  of  the  results  themselves.  Most  of  these  results 
may  be  expressed  indifferently  in  terms  of  one  theory 
or  the  other,  and  where  they  cannot  we  shall  use  the 
terminology  most  suited  to  the  particular  statements  to 
be  made.  The  facts  are  important  and  will  persist, 
while  the  theories  that  interpret  them  are  always  in 
constant  flux.  We  shall  be  primarily  concerned  with 
facts,  and  the  theories  will  be  considered  only  where  they 
serve  to  make  clear  the  facts. 


CHAPTER  II 

THE  NERVOUS.  SYSTEM— CORD  AND  BRAIN  STEM 

Broadly  speaking,  the  physical  basis  of  mind  is  to  be 
found  in  the  nervous  system.  In  a  very  general  sense, 
the  nervous  system  is  the  organ  of  mind.  When,  how- 
ever, we  approach  it  from  the  physical  side,  it  is  also  the 
organ  that  makes  possible  the  activities  of  the  body, 
that  permits  external  stimuli  to  act  upon  the  muscles  and 
coordinates  the  different  movements  so  that  they  may 
bring  about  harmonious  and  unified  action.  An  imder- 
standing  of  the  action  and  even  of  the  structure  of  the 
nervous  system  is  very  much  easier  if  we  keep  the  em- 
phasis upon  the  relation  of  the  nervous  system  to  bodily 
movement,  —  treat  it  first  for  itself,  —  than  if  we  think 
of  it  in  its  relation  to  consciousness.  The  problem  of 
the  relation  of  body  and  mind  may  be  taken  up  when  we 
know  more  of  body.  The  nervous  system  in  vertebrates 
is  made  up  of  the  brain  and  spinal  cord  with  the  sensory 
and  motor  nerves  that  extend  from  these  central  organs 
to  the  sense  organs  and  muscles.  The  brain  fills  the 
upper  part  of  the  skull  while  th^  spinal  cord  is  found  in 
the  spinal  column.  The  details  of  the  structures  can  be 
understood  more  easily  if  we  consider  them  later  in 
connection  with  their  development  in  the  race  and  in 
the  individual. 

IS 


l6  FUNDAMENTALS    OF   PSYCHOLOGY 

Life  Processes  in  Cells.  —  In  the  higher  animals  it 
may  be  said  that  practically  all  action  is  made  possible 
by  the  intervention  of  nerve  tissue,  but  this  does  not 
hold  in  the  lowest  forms.  It  is  much  easier  to  under- 
stand the  action  of  higher  animals  and  of  the  nervous 
structures  themselves  if  we  begin  with  the  organisms 
that  do  not  possess  nerve  tissue,  that  show  no  signs  of 
development  whatever.  It  may  be  asserted  that  the 
type  of  organism  from  which  all  the  higher  forms  have 
developed  is  that  shown  in  the  single-celled  animals,  or 
protozoa.  One  that  is  most  frequently  used  to  illustrate 
the  type  is  the  amoeba.  This  is  an  organism  composed 
of  a  single  cell.  It  is  merely  a  drop  of  Hquid  of  unknown 
but  highly  complex  chemical  composition  contained  in  a 
delicate  semipermeable  membrane.  Since  it  is  the  orig- 
inal matter  from  which  all  tissue  is  developed,  it  is  known 
as  protoplasm.  We  know  only  that  protoplasm  is 
made  up  of  highly  unstable  chemical  compounds,  mostly 
hydrocarbons,  but  the  different  components  have  never 
been  completely  isolated  or  analyzed.  Whatever  the 
composition  of  this  chemical  substance,  it  is  constantly 
undergoing  change.  It  takes  to  itself  other  organic  com- 
pounds and  oxygen  and  gives  off  carbonic  acid.  It  is 
constantly  taking  something  from  the  medium  in  which 
it  lives  and  giving  off  waste  products.  Both  of  these 
changes  take  place  through  the  semipermeable  membrane 
by  a  process  that  the  physicist  calls  osmosis.  Within  the 
protoplasm  is  a  darker  spot  that  is  known  as  the  nucleus. 
This  nucleus  is  closely  connected  with  the  nutritive  pro- 
cesses and  the  subdivision  of  the  cell.  What  the  lexact 
and  detailed  processes  are  l^y  which  all  of  the  changes 


THE    NERVOUS    SYSTEM  —  CORD    AND    BRAIN    STEM        1 7 

take  place  we  do  not  know,  any  more  than  we  know 
exactly  the  composition  of  the  parts.  We  do  know  that 
some  chemical  processes  must  go  on  within  the  cell,  that 
the  materials  involved  are  admitted  to  the  cell  by  osmosis 


Fig. 


Amoeba   chasing   and   attempting   to   ingest   an   euglena.     (From 
Jennings.) 


through  the  membrane,  and  that  these  processes  taken 
together  make  possible,  if  they  do  not  constitute,  what  we 
call  hfe. 

The  Activities  of  Protozoa.  —  If  we  study  the  activities 
of  one  of  the  unicelliflar  organisms,  we  find  that  in  a 
simple  way  it  can  do  almost  everything  that  the  most 
c 


1 8  FUNDAMENTALS    OF   PSYCHOLOGY 

highly  organized  animal  can,  and  that  it  follows  the 
same  fundamental  laws  of  behavior.  It  takes  nourish- 
ment, it  breathes,  and,  what  is  most  important  from  our 
point  of  view,  it  moves  to  find  the  conditions  best  suited 
to  its  needs.  When  certain  particles  come  into  contact 
with  its  membrane,  it  enfolds  them  and  the  process  of 
digestion  through  the  membrane  of  the  cell  begins.  If 
other  particles  come  into  contact  with  it,  it  moves 
quickly  away.  When  in  contact  with  a  solid  body,  it 
may  send  out  a  prolongation  of  its  body  in  the  form  of  a 
foot  or  -What  is  kno^n  as  a  pseudopojd  (false  foot)  which 
attaches  itself  to  the  surface,  and  the  whole  body  then 
draws  itself  up  to  the  foot,  which  is  then  again  withdrawn 
into  the  rest  of  the  body.  The  single  cell  is  stomach, 
lung,  and  organ  of  locomotion  in  one. 

When  one  looks  at  the  details  of  its  movements,  it 
approaches  more  nearly  the  characteristics  of  the  higher 
organisms.  When  stimulated  gently  by  a  soHd  surface, 
its  activity  is  not  changed,  but,  if  the  excitation  is 
stronger,  it  at  once  stops  all  movement  and  rolls  up  into 
a  ball.  If  the  stimulation  is  continued,  it  may  send  out 
a  pseudopod  on  the  opposite  side  and  roll  away  from  the 
stimulus.  In  these  two  ways  the  protozoa  respond  to 
light,  heat,  the  'motion  of  the  Hquid  medium,  the  attrac- 
tion of  gravitation,  and  to  the  presence  of  chemicals  in 
the  hquid.  In  general,  beneficial  stimuli  have  no  effect, 
while  harmful  stimuli  cause  a  movement  that  removes 
the  organism  from  its  neighborhood.  Certain  organisms, 
the  S  ten  tor  that  Jennings  worked  with,  e.g.,  modify  their 
reactions  in  accordance  with  the  results  of  the  earher 
reactions,  and  thus  give  the  first  evidence  of  learning. 


THE    NERVOUS    SYSTEM  —  CORD    AND    BRAIN    STEM 


19 


If  we  use  variability  of  response  as  marking  intelligence, 
this  may  be  regarded  as  an  intelligent  act.  The  first 
response  of  the  Stentor  when  stimulated  is  to  -withdraw 
into  its  tube.  After  this  has  been  repeated  several  times, 
it  changes  its  form  of 
response  to  bending  to 
one  side  to  escape  the 
contact.  Later  it  may, 
when  strongly  and  re- 
peatedly stimulated, 
loosen  its  hold  on  the 
tube  and  svdm  away. 
These  latter  responses 
were  called  out  by  per- 
mitting water  mixed 
vdih  carmine  particles 
to  reach  its  disk. 

Each  of  these  re- 
sponses is  to  be  thought 
of  as  the  result  of  the 
transfer  of  a  chemical 
stimulus  from  the  point 
of  stimulation  to  a 
more  or  less  remote 
portion  of  the  cell  where 
the  protoplasm  or  mem- 
brane is  made  to  un- 
dergo chemical  change.  The  exact  nature  of  the  change 
is  not  known.  Most  of  the  very  simple  explanations 
offered  have  proven  themselves  inadequate.  If  the  sim- 
ple reactions  are  to  be  explained  in  terms  of  the  com- 


FiG.  2.  —  Stentor   stimulated   by  carmine 
particles.     (From  Jennings.) 


20  FUNDAMENTALS    OF   PSYCHOLOGY 

position  of  the  protoplasm  and  the  physical  constitution 
of  the  environment,  it  is  necessary  to  recognize  that 
that  composition  is  changed  in  the  S  ten  tor  by  earher 
responses.  At  the  present  stage  of  our  knowledge 
we  can  do  no  more  than  express  the  belief  that  a  chemical 
or  physical  explanation  may  some  day  be  found.  Mean- 
time we  may  use  the  action  of  these  simple  organisms 
as  a  type  of  the  action  of  cells  in  general. 

Man  a  Colony  of  Cells.  —  These  responses  are  impor- 
tant for  us  from  the  fact  that  one  may  think  of  all  of 
the  higher  organisms  as  compounded  of  cells  like  these 
simple  unicellular  organisms,  which  have  undergone 
various  modifications  as  a  result  of  living  together  in  a 
colony,  but  still  retain  many  of  the  characteristics  of 
the  original  free-swimming  protozoa.  For  our  present 
purposes,  the  body  of  man  may  be  pictured  as  a  mass  of 
cells  in  which  each  class  has  developed  peculiarities 
that  fit  it  to  fulfil  some  one  function.  With  increased 
capacity  for  this  function,  others  of  the  primitive  capa- 
bihties  have  been  lost.  Nevertheless  the  rudiments  of 
all  the  capacities  of  the  complex  organisms  are  to  be 
found  in  the  unicellular  organisms.  In  the  body,  the 
nerve  cells  are  among  the  least  modified.  Unlike  the 
bone  cells,  e.g.,  that  become  so  filled  with  salts  as  to 
retain  but  slight  similarity  to  the  original,  the  nerve 
cells  lack  motion  alone  of  the  capacities  of  the  proto- 
type. Only  certain  of  the  blood  corpuscles  retain  more 
of  the  original  properties.  The  leucocyt^^,  or  white 
blood  corpuscles,  seem  to  live  almost  as  independent  an 
existence  in  the  blood  as  the  amoeba  in  its  watery 
medium* 


THE    NERVOUS    SYSTEM  —  CORD   AND    BRAIN    STEM        21 

Types  of  Neurones.  —  The  cells  of  the  nervous  sys- 
tem have  retained  especially  the  sensitivity  and  con- 
ductivity of  the  original  organisms.  In  form,  the 
elements  of  the  nervous  system,  known  as  neurones 
(also  spelled  neurons),  consist  of  a  central  cell,  the  rep- 
resentative of  the  cell  body,  and  numerous  processes 


Fig.  3.  —  A  group  of  human  nerve-cells  drawn  to  the  same  scale,  a,  small 
cell  from  the  ventral  horn  of  the  cord;  i,  cell  from  Clarke's  column;  c,  small 
nerve-cell  from  tip  of  dorsal  horn,  thoracic  cord;  d,  spinal  ganglion  cell, 
cervical  root;  e,  three  granules  from  cerebellum;  /,  Purkinje  cell  from 
cerebellum;  g,  small  pyramidal  cell  from  second  layer  of  central  gyri  of 
cortex;  h,  giant  pyramidal  cell  from  same  region.  (From  Donaldson,  after 
Adolf  Meyer.) 


that  extend  in  all  directions  from  that  cell  body.  The 
cell  body  is  of  a  more  or  less  irregular  shape  and  varies 
in  diameter  from  about  2W  to  iV  of  a  miUimetre.  The 
shapes  can  be  best  seen  from  the  accompanying  dia- 
grams. Within  the  body  of  the  cell  can  be  made  out 
a  nucleus  and  a  nucleolus,  as  in  all  cells.  Within  the 
body  of  the  protoplasm  are  small  particles  that  stain 


22 


FUNDAMENTALS    OF   PSYCHOLOGY 


easily,  named  Nissl  or  tigroid  bodies,  the  former  after 
their  discoverer.  In  many  cells  can  also  be  seen  fine 
fibrils  that  run  through  the  bodies  of  the  cells  and  into 
the  processes.  It  is  not  possible,  however,  to  assert 
positively  what  function  these  different  parts  of  the 
cell  have.  The  nucleus  and  Nissl  bodies  are  probably 
closely  connected  with  the  nutrition  of  the  cell.  Some 
theories  assign  a  highly  important 
function  to  the  fibrils,  but  the 
balance  of  opinion  seems  opposed 
to  regarding  any  one  part  of  the 
cell  as  the  fundamental  seat  of  its 
activity.  We  cannot  as  yet  an- 
alyze the  action  of  the  cell  into 
elements,  but  must  think  of  it  as 
acting  as  a  unit. 

Axones  and  Dendrites.  —  The 
processes  or  extensions  of  the  neu- 
rones are  of  two  sorts,  distinguished 
rather  by  function  than  by  struc- 
ture. One,  which  serves  to  conduct 
impressions  away  from  the  cell 
body,  is  usually  long,  with  relatively  few  branches,  and 
these  at  right  angles  to  the  main  stem.  It  is  called  the 
axone  (also  spelled  axon).  The  axone  has  at  ats  end 
a  number  of  short  branches,  each  of  which  is  probably 
continuous  with  a  fibril  in  the  axone,  the  end  brush. 
The  other  is  usually  made  up  of  a  number  of  fibres 
much  shorter  and  much  branched,  is  in  fact  usually  a 
thick  network  like  the  roots  of  a  tree,  an  appearance 
that   gives   the   whole   its   name,   the   dendrite.     This 


"  Nucleus. 


Fig.  4.  —  "  T-shaped  " 
cell  from  spinal  ganglion 
of  frog.  (From  Boehm- 
Davidoff-Huber's  "  His- 
tology." 


THE    NERVOUS    SYSTEM  —  CORD    AND    BRAIN    STEM       23 

usually  carries  impressions  to  the  cell  body.     The  axones 
may  be  of  considerable  length.     A  single  axone  extends 


Fig.  5.  —  Cells  from  the  cord  of  a  rabbit,  showing  internal  structures. 
A,  B,  C,  motor  cells;  D,  small  cell  from  the  spinal  root;  a,  bundles  of  neuro- 
fibrils; c,  perinuclear  plexus;  d,  the  empty  areas  correspond  to  the  Nissl 
bodies;  e,  section  of  a  dendrite,  showing  similarity  to  cell  tissue.  (From 
Cajal.) 

from  the  brain  to  the  lower  cord  in  the  case  of  the  motor 
fibres  and  sensory  axones -from  the  cord  to  the  medulla. 


24 


FUNDAMENTALS  OF  PSYCHOLOGY 


The  axones  carry  impulses  away  from  the  cells.  The 
dendrites  are  nearly  always  relatively  short,  less  than  a 
millimetre  in  length.  The  one  striking  exception  is 
found  in  the  case  of  the  dendrites  of  sensory  neurones 
in  the  posterior  roots.  These  are  neurones  whose 
cells  are  found  in  the  masses  of  nerve  tissue  near  the 
cord,  known  as  the  spinal  ganglia.  They  serve  to 
transfer  impressions  from  the  organs"  of  the  skin  and 

lower  body  to  the  cord  and^ 
medulla.  The  process  that 
runs  to  the  skin  may  be  two 
feet  or  more  in  length,  extend- 
ing from  the  skin  of  the  toe, 
for  example,  to  the  T-shaped 
cell  body  in  a  spinal  gangHon 
in  the  lower  part  of  the  back. 
In  appearance  it  is  not  to  be 
distinguished  from  the  fibre  of 
an  axone,  but  its  function  is 
to  carry  an  impulse  to  the 
cell,,  the  function  of  a  den- 
drite. Whether  it  shall  be 
classed  as  an  axone  with  the  function  of  a  dendrite  or 
a  dendrite  with  the  form  of  an  axone  is  somewhat  in 
dispute  among  anatomists.  We  can  be  content  to 
leave  the  question  of  naming  open,  and  look  upon  it 
merely  as  an  exception  to  the  general  rule. 

The  Sheaths  of  the  Axones.  —  The  axones  do  not 
show  a  homogeneous  cross  section,  but  consist  of  several 
parts.  In  the  centre  is  a  core  of  protoplasm  contin- 
uous with  the  structure  of  the  cell  body.     In  it  may  be 


Fig.  6.  —  Neuroglia  cell. 
In  this  preparation  the  cell  is 
prominent.  In  the-  more  usual 
method  of  staining,  the  fibres  are 
more  striking  and  give  the 
so-called  spider  cells.  (From 
Huber,  after  Joseph.) 


THE    NERVOUS    SYSTEM  —  CORD   AND    BRAIN    STEM       25 

traced  the  minute  fibrils  that  were  mentioned  above 
as  found  in  the  cell.  About  this  central  core  of  nervous 
tissue  are  found  one  or  two  coverings  or  sheaths.  One, 
the  outer,  known  as  the  neurilemma,  or  sheath  of 
Schwann,  is  a  thin  white  layer,  segmented  or  notched  at 
intervals.  Many  fibres  have  within  this,  outer  sheath 
a  thicker  coating  of  fatty  substance  known  as  the  medul- 
lary or  myelin  sheath.  This  is  absent  in  the  nerves  of 
the  sympathetic  system  and  at  the  early  stages  of  the 


^ 


Fig.  7.  —  Longitudinal  and  transverse  sections  of  a  medullated  nerve  fibre. 
The  myelin  sheath  is  shown  in  black ;  the  central  protoplasm  shows  its  fibrous 
structure.     (From  Barker,  after  Biedermann.) 

development  of  the  fibres  in  the  brain.  The  primitive 
sheath  is  found  on  the  peripheral  nerves,  but  is  lacking 
within  the  central  nervous  system.  The  axone  is  bare, 
too,  for  a  short  distance  after  it  leaves  the  cell  body 
and  the  end  brush  is  also  always  bare.  It  seems  then 
that  the  central  core  alone  is  essential  to  the  conduc- 
tion of  a  nervous  impulse.  Flechsig  has  inferred  that 
the  medullary  sheath  is  necessary  for  the  action  of 
brain  fibres  from  the  fact  that  this  sheath  develops 
successively  on  different  groups  of  fibres,  as  the  indi- 
vidual grows  older  before   and   after  birth,   and   that 


26  FUNDAMENTALS   OF   PSYCHOLOGY 

fibres  continue  to  be  meduUated  up  to  and  beyond  middle 
age.  The  facts  that  some  fibres  are  always  without 
this  sheath  and  that  animals  can  learn  before  their 
cerebral  fibres  are  medullated  make  its  importance 
somewhat  doubtful.  The  central  core  is  bare  at  the 
ends  of  the  end  brush  where  it  comes  in  contact  with 
the  dendrite  of  another  neurone.  The  central  core, 
then,  may  be  regarded  as  the  path  of  the  impulse, 
and  the  sheaths  as  largely  protective.  In  a  peripheral 
nerve  several  thousands  of  these  fibres  may  be  united. 
In  the  optic  nerve  it  is  estimated  that  there  are  ioo,ooc 
of  them  grouped  together.  Between  the  nerve  cells 
are  numerous  cells  of  a  different  character,  the  neuroglia 
cells.  They  are  supposed  to  have  no  part  in  the  con- 
ductivity of  the  nervous  system,  but  are  supposed  to 
constitute  supporting  structures.  Their  exact  function 
is  not  known.     Their  shapes  may  be  seen  in  Figure  6. 

The  General  Outlines  of  the  Nervous  System.  — 
The  nervous  system  of  man  is  merely  a  conglomeration 
of  these  neurones  held  together  by  their  own  cohesion 
and  the  pressure  of  the  bones  and  other  surrounding 
tissues.  The  pecuHarities  of  appearance  of  the  differ- 
ent structures  are  due  to  the  way  in  which  the  different 
elements  are  combined  to  constitute  the  masses.  As 
one  looks  at  the  nervous  system  of  a  mammal,  one 
may  distinguish  three  parts.  The  largest  is  the  c£ie-, 
brum,  which  fills  the  upper  portion  of  the  skull,  next 
below  is  the  braijL^stem,  so  called  because  it  may  be 
regarded  as  supporting  the  brain  proper.  The  largest 
part  of  this  is  the  cerebellum,  which  lies  in  man  just 
beiow  the  cerebrum,  although  it  is  attached  to  Uie  brain 


THE    NERVOUS    SYSTEM  —  CORD   AND    BRAIN    STEM       27 


Cer 


.u  •5'  ^-""^^^  nervous  system  as  a  whole.  On  the  left  it  is  seen  from 
the  side  m  position  in  the  body;  on  the  right  exposed  and  seen  from  the 
treat.  Cer  the  cerebrum;  Ci.,  the  cerebellum ;  \S/>.C.,  the  spinaUord ;  P 
the  pons;  M  the  medujla.  The  other  letters  designate  nerve  trunks  going 
:o  :he  ^entral  nervous  system  and  connections  with  the  sympathetic  system. 


28  FUNDAMENTALS    OF    PSYCHOLOGY 

stem  below  several  of  the  other  important  structures. 
In  the  brain  stem  between  the  base  of  the  cerebrum  and 
the  point  of  attachment  of  the  cerebellum  are  the  corpora 
quadrigemina  and  the  thalami.  The  latter  is  at  the 
base  of  the  cerebrum,  the  former  just  below  it.  The 
lowest  and  smallest  portion  of  the  brain  stem  is  the 
medulla.  Just  below  that  is  the  spinal  cord,  the  third 
of  our  main  divisions,  which  extends  downward  the 
full  length  of  the  spinal  column.  The  position  of  these 
more  prominent  orgafls  should  be  carefully  studied  in 
Figure  d:^  Superficially  regarded,  the  most  striking  dif- 
ferences between  different  structures  are  in  the  colors. 
The  cortex,  or  outer  layer  of  both  cerebrum  and  cere- 
bellum, is  gray ;  the  cord  is  white.  The  gray  color  is 
given  by  masses  of  cell  bodies  closely  crowded  together, 
while  the  white  color  is  given  by  the  white  sheaths  of 
the  nerve  fibres.  Similarly,  a  section  through  any  part 
of  the  central  nervous  system  will  show  masses  of  white 
matter  and  other  masses  of  gray  matter.'  In  the  cord 
the  centre  is  gray,  the  more  peripheral  parts  white ;  in 
the  cerebrum  the  relation  is  reversed,  but  in  each  case 
the  gray  matter  is  a  mass  of  cells,  the  white  a  mass  of 
axones.     Small  masses  of  cells  are  known  as  ganglia. 

The  structures  of  the  nervous  system  may  also  be 
grouped  with  reference  to  function.  From  this  stand- 
point cells  and  fibres  may  be  divided  into  sensory  or 
centripetal,  associative  or  commissural,  and  motor  or 
centrifugal.  The  first  group  are  connected  with  sense 
organs,  directly  or  indirectly.  The  axones  conduct 
from  the  periphery*^ to  the  centre.  The  first  cells  of 
sensory  ganglia  are  outside  of  the  central^nervous  sys- 


THE    NERVOUS    SYSTEM  —  CORD    AND    BRAIN    STEM       29 

tern,  either  in  the  sense  organ,  or  in  gangha  near  the 
central  nervous  system,  and  their  axones  connect  with 
other  cells  nearer  the  brain.  The  comrnissural  cells 
and  fibres  transfer  the  impression  from  sensory  cells  to 
motor  cells.  .The  motor  or  centrifugal  neurones  stand 
in  immediate  connection  with  the  muscles,  or  with 
neurones  which  serve  to  innervate  the  muscles,  —  are 
members  of  the  chain  that  conducts  impulses  from  the 
centres  outward.  The  neurones  that  possess  these 
different  functions  cannot  be  distinguished  structurally. 
One  can  make  no  general  statement  as  to  what  char- 
acterizes sensory,  motor,  or  commissural  neurones. 
The  functions  depend  rather  upon  the  connections  in 
which  the  neurones  are  found  than  upon  their  structures. 
Development  of  Embryo.  —  To  understand  the  struc- 
tural relations,  one  must  go  back  to  the  development 
of  the  nervous  system  in  connection  with  the  embry- 
ology of  the  organism  as  a  whole.  Many  relations, 
very  complicated  in  the  developed  organism,  are  very 
simple  in  the  earher  stages.  The  complexities  are  caused 
by  the  conditions  of  growth.  Our  sketch  of  the  devel- 
opment must  be  very  brief,  with  many  omissions,  but. 
even  this  may  be  helpful  at  some  points.  The  com-' 
plete  adult  is  developed  from  an  original  cell,  the  fer-' 
tilized  ovum,  by  a  process  of  subdivision.  The  original 
cell  divides  into  two,  each  of  these  into  two,  and  so  on. 
At  first  the  derived  cells  are  exactly  like  the  original 
so  far  as  can  be  made  out.  They  are  grouped  com- 
pactly. The  first  sign  of  differentiation  comes  when  a 
hollow  appears  within  the  mass,  and  the  enclosing  cells 
divide  into  two  layers,  an  outer,  the  ectoderm,  and  an 


30 


FUNDAMENTALS    OF    PSYCHOLOGY 


inner,  the  entoderm.  Soon  a  third  intermediate  layer 
develops  from  the  others  to  constitute  the  mesoderm. 
These  layers  may  be  distinguished  throughout  the  re- 
maining development  and  give  rise  to  different  parts  of 


Fig.  q.  —  Embryo  of  a  rabbit  at  eight  days  to  show  the  neural  groove. 
rj  is  the  neural  groove ;  h,  the  region  in  which  the  fore-brain  is  to  develop. 
(From  Kolliker.) 


the  organism.  The  entoderm  gives  rise  to  the  inner 
wall  of  the  internal  organs,  and  to  certain  organs,  as 
the  liver  and  pancreas.  From  the  mesoderm  develop 
the    supporting    structures,    com 


THE    NERVOUS    SYSTEM  —  CORD   AND    BRAIN    STEM       3 1 

muscle,  and  the  body  of  most  of  the  internal  organs. 
The  outer  layer  and  its  appendages  develop  into  the 
skin,  the  mucous  membrane  of  the  mouth  and  nose, 
and,  what  concerns  us  most,  into  the  nervous  system  and 
the  essential  parts  of  the  sense  organs. 


Fig.  10.  —  Closing  of  the  neural  groove.  The  figure  at  the  top  shows  the 
groove  still  open;  in  the  next,  the  sides  approximate  each  other;  in  the  lowest, 
the  closure  is  complete.  G,  the  cells  from  which  the  spinal  ganglia  develop ; 
a,  the  ectoderm ;   b,  the  epithelial  Uning  of  the  medullary  tube. 


IS 


The   Development  of  the  Nervous   System.  —  It 

interesting  to  note  how  the  outer  layer  of  the  embryo 
gives  rise  to  the  nervous  system  which  finally  becomes 
embedded  so  deeply  in  the  structure  of  the  body.     Very 


32 


FUNDAMENTALS   OF  PSYCHOLOGY 


early  in  the  embryonic  life,  within  the  first  two  weeks, 
there  appears  upon  the  surface  of  the  embryo  a  slight 
depression  known  as  the  neural  groove  (Fig.  9).  This 
gradually  grows  deeper,   and  finally   the  upper  edges 

grow  together 
and  form  the 
neural  tube 
(Fig.  10). 
From  the  walls 
of  this  tube 
the  entire  ner- 
vous system 
grows.  The 
forward  end 
becomes  the 
brain,  the 
other  longer 
portion,  the 
spinal  cord. 
The  cells  that 
Hne  the  tube 
give  off  first 
masses  of  cells 
with  radiating 
fibres     that 


Fig.   II.  —  The   ependymal  or  supporting  structure  of 
the  embryo  cord.     (From  Cajal.) 


serve  as  a  supporting  structure  or  scaffold  (Fig.  11). 
Some  at  least  of  these  develop  later  into  neuroglia  cells, 
the  supporting  tissue  of  the  central  nervous  system. 
This  first  supporting  structure  takes  the  general  form 
and  may  be  said  to  prepafe  the  way  for  the  truly 
nervous  structure.     After  the  supporting  or  ependymal 


THE   NERVOUS    SYSTEM  -^  CORD   AND   BRAIN    STEM      33 


structure  is  well  de- 
veloped, further  divi- 
sion of  the  cells  Hning 
the  tube  gives  rise  to 
embryo  neurones  or 
neuroblasts.  These 
make  their  way  out- 
ward toward  the  posi- 
tion they  are  to  oc- 
cupy in  the  adult 
cord.  As  the  neuro- 
blasts develop  they 
send  out  processes, 
axones  and  dendrites, 
surround   the  mass  of 


Fig.  13.  —  Schematic  section  of  embr>'o 
cord.  A,  anterior  or  motor  root ;  B,  posterior 
root ;  C,  central  canal ;  a,  epithelial  wall ;  h, 
neuroblasts  or  embryo  neurons;  c,  the  pri- 
mordial white  matter.     (Cajal,  after  His.) 


Fig.  12.  —  Epithelial  cells  lining  the  neural 
tube  and  germinal  cells,  A ,  that  have  developed 
from  them.     (From  Cajal,  after  His.) 

The  axones  grow  outward  and 
neuroblasts.  A  section  of  ^  the 
cord  at  the  end  of  the 
first  month  shows  a 
layer  of  epithelial  cells 
about  the  central  tube, 
farther  out  the  neuro- 
blasts and  then  the 
axones  (Fig.  13). 
Everywhere  in  the 
brain  as  well  as  here 
in  the  cord  the  prin- 
ciple holds  that  the 
processes  are  out- 
growths of  the  cell 
bodies.  The  axones 
spread  from  the  cells 
up    the    cord    to    the 


34 


FUNDAMENTALS    OF   PSYCHOLOGY 


higher  centres,  and  on  the  ventral  side  in  particular  out- 
ward to  the  muscles,  even  to  the  remote  parts  of  the  body. 
Meanwhile  the  sensory  neurones  are  developing  in  the 


Fig.  14.  —  Development  of  dorsal  root  ganglion  with  cord.  A,  motor 
nerve ;  B,  posterior  root,  fibres  from  ganglion  entering  cord ;  £,  '  T  '-shaped  cells 
of  dorsal  ganglion  in  their  bipolar  stage;  e,  sensory  nerve,  dendrites  of 
'  T  '-shaped  cells.     (From  Cajal.) 


dorsal  gangha.  When  the  walls  of  the  neural  groove 
grow  together  to  form  the  tube,  portions  of.  the  ecto- 
derm are  cut  off  both  from  the  tube  and  from  the  sur- 


THE   NERVOUS    SYSTEM 


CORD   AND   BRAIN    STEM 


35 


face.  They  move  away  from  the  median  plane,  and 
are  surrounded  by  mesoderm  tissue.  The  original 
ectoderm  cells  give  rise  to  neurones.  At  first  the  pro- 
cesses of  the  neurones  grow  out  from  either  end;  one 
goes  outward  to  the  end  organ  in  skin  and  muscle,  the 
other  grows  into  the  cord  and  sends  fibres  upward  in 
the  dorsal  white  columns  or  into  the  central  gray. 
Later  in  the  development,  the  two  processes  grow  to- 
gether for  a  short  distance  from  the  cell  and  then  grow 
off  at  right  angles  to 
the  original  stem.  They 
thus  resemble  a  'T,'  and 
the  cells  are  known  as 
the  '  T  '-shaped  cells. 
Before  birth  the  germi- 
nal layer  stops  giving 
rise  to  new  cells  and 
forms  a  single  layer  of 
cells  lining  the  central 
tube. 

The  Development  of  the  Anterior  Portion  of  the 
Neural  Tube.  —  The  growth  of  the  forward  end  of  the 
neural  tube,  the  part  from  which  the  brain  develops, 
follows  much  the  same  plan.  The  supporting  struc- 
ture and  the  neuroblasts  appear  as  in  the  cord.  One 
difference  should  be  emphasized,  however,  that  the 
neuroblasts  are  projected  farther  from  the  tube  and  the 
axones  grow  inward  and  extend  up  or  down  within  the 
masses  of  cells.  In  consequence  the  white  matter  is, 
for  the  most  part,  within ;  the  gray,  on  the  surface. 
One  other  problem  upon  which   development   throws 


Fig.  15.  —  Development  of  brain  vesicles 
seen  from  above.  The  hemispheres  may 
be  seen  growing  from  sides  of  fore-brain. 
(From  His.) 


36 


FUNDAMENTALS   OF  PSYCHOLOGY 


considerable  light  is  in  the  longitudinal  arrangement 
of  the  parts.  By  the  end  of  the  second  week,  the  for- 
ward end  of  the  tube  bends  sharply  downward,  ven- 
trally,  and  becomes  divided  into  separate  pouches  or 
vesicles.  At  first  three,  later  five,  vesicles  are  to  be 
seen.     These  are  marked  by  constrictions  in  the  tube 


Cerebrum 


Thalamus 


Corpora  Quadricjennna 


Forebram 


Tween  braxn. 


Fig.  1 6.  —  The  five- vesicle  stage  of  the  human  brain,  giving  names  of  vesicles : 
fore-brain,  tween-brain,  etc.,  and  the  parts  of  the  adult  brain  that  develop  from 
each.     (After  His.) 


at  four  places.  Two  most  marked  are  just  before  and 
just  behind  the  bend  in  the  tube.  The  vesicle  between 
is  the  mid-brain.  The  region  in  front  is  divided  by  a 
shallower  groove  into  end-brain  or  fore-brain,  and  tween- 
brain,  while  the  portion  just  behind  is  similarly  divided 
into  the  hind-brain  and  after-brain.  These  early  divi- 
sions give  the  name  to  the  corresponding  parts  of  the 


THE   NERVOUS    SYSTEM  —  CORD   AND   BRAIN   STEM       37 

adult  nervous  system.  The  fore-brain  develops  into 
the  cerebrum,  the  tween-brain  into  the  thalamus  among 
others,  the  mid-brain  into  the  corpora  quadrigemina 
and  other  structures,  the  hind-brain  into  the  cerebellum 
and  pons,  and  the  after-brain  gives  rise  to  the  medulla. 
In  each  the  walls  are  very  much  thickened  and  at  many 
points  there  are  very  large  outgrowths,  but  all  grow 
from  the  Kning  of  the  original  tube  by  the  process  of 
cell  di\dsion  indicated  above.  The  original  cavity  under- 
goes changes  of  shape  in  many  places.  It  becomes 
much  heightened  in  the  hind-brain  to  constitute  the 
fourth  ventricle,  in  the  mid-brain  it  retains  its  original 
shape,  and  continues  small  as  the  aqueduct  of  Sylvius. 
It  broadens  in  the  tween-brain  to  the  third  ventricle 
and  assumes  a  compHcated  bifurcated  form  in  the  cere- 
bral hemispheres,  the  lateral  or  first  and  second  ven- 
tricles. Nevertheless  it  remains  continuous  throughout 
from  the  lateral  ventricles  in  front  to  the  bottom  of 
the  spinal  cord.  It  is  filled  everywhere  with  the  cerebro- 
spinal fluid. 

One  pecuharity  deserves  special  mention,  —  the  devel- 
opment of  the  cerebral  hemispheres.  They  appear 
early  as  lateral  swelHngs  on  the  end-brain.  These  grow 
first  to  the  side,  then  upward  and  back  until  they  cover 
mid-brain  and  cerebellum,  an  outgrowth  of  the  original 
hind-brain.  The  two  hemispheres  are  distinct  from 
the  beginning.  They  merely  come  into  contact  along 
the  median  fissure ;  there  is  no  organic  connection 
between  them  except  at  the  base.  In  this  growth  back- 
ward, the  cerebral  hemispheres  are  folded  here  and 
there,  and  these  folds  account  for  some  of  the  perma- 


38 


FUNDAMENTALS  OF  PSYCHOLOGY 


nent  markings  upon  its  surface.  Most  striking  of  these 
is  the  fissure  of  Sylvius.  This  can  be  seen  from  the 
second  month.  It  develops  in  very  much  the  same  way 
as  the  median  fissure  from  the  growing  together  of  one 
outgrowth  of  the  frontal  portion  and  the  lateral  portion 
of  the  more  posterior  portion.  When  these  grow  to- 
gether on  the  surface,  they  leave  considerable  portions 


Fig.  17.  —  Shows  development  of  the  hemisphere,  the  left  figure  at  three 
months,  the  right  at  six  months,  fs  is  the  fissure  of  Sylvius ;  c,  the  cerebellum ; 
m,  the  mid-brain.     (From  KolUker.) 

of  their  superficial  areas  in  juxtaposition  well  below  the 
surface.  The  walls  of  this  deep  fissure  constitute  the 
island  of  Reil. 

In  the  course  of  the  development,  then,  we  find  neu- 
rones originating  from  the  cells  that  lined  the  central 
tube.  In  the  neighborhood  of  the  tube,  masses  of 
nerve  cells  arise,  now  in  a  continuous  structure  as  in 
the  cord,  now  with  exuberant  growth  in  comparatively 
isolated  regions  separated  from  other  cell  masses   by 


THE   NERVOUS    SYSTEM  —  CORD   AND   BRAIN    STEM      39 

regions  of  white  matter,  as  in  the  cerebrum  and  cere- 
bellum. From  these  cells  the  axones  grow  out  for  long 
distances  to  the  sense  organs  and  to  the  muscles  on  the 
peripheral  side  and  to  the  other  cell  masses  in  central 
structures,  until  sense  organ  is  connected  with  muscle, 
and  centre  with  centre  throughout  the  organism.  The 
problem  of  understanding  the  nervous  system  is  very 
largely  one  of  tracing  these  connecting  paths  from  sense 
organ  to  centre,  and  from  centre  to  centre  within  the 
entire  system. 

The  Nature  of  the  Nerve  Impulse.  —  The  function 
of  a  nerve  unit  or  neurone  is  to  conduct  from  sense  organ 
to  muscle.  The  question  naturally  arises,  what  is  con- 
ducted? The  answer  to  this  is  not  fully  determined. 
In  fact,  theories  vary  from  decade  to  decade.  An  indi- 
cation that  will  at  least  limit  the  possibiHties  is  obtained 
from  the  rate  of  propagation.  This  has  been  determined 
to  be  from  loo  to  perhaps  230  metres  per  second.  That 
at  once  removes  the  possibiHty  that  the  process  is  a 
simple  electrical  one.  One  other  fact  in  connection 
with  the  determination  of  the  character  of  the  nervous 
impulse  is  the  extremely  small  evidence  of  fatigue 
and  the  small  amount  of  nutriment  required  by  the 
axone  in  its  propagation.  Nerves  have  been  stimulated 
for  four  or  five  hours  and  at  the  end  of  that  time  have 
been  just  as  ready  to  respond  as  at  the  beginning.  It 
has  also  been  found  impossible  to  discover  any  heat 
as  a  result  of  their  action,  and  the  amount  of  carbon 
dioxide  given  off  is  extremely  slight.  These  state- 
ments hold  only  for  the  conducting  nerve  fibre,  not  for 
the  cell.     Evidently,  then,  the  energy  changes  involved 


40  FUNDAMENTALS    OF   PSYCHOLOGY 

in  conduction  are  relatively  slight.  Still  another  fact 
that  must  be  taken  into  consideration  by  any  final 
theory  is  the  electric  current  (current  of  action)  that  is 
produced  whenever  the  nerve  is  stimulated.  If  the  cut 
end  of  a  nerve  is  connected  with  its  sheath  through  a 
delicate  galvanometer,  it  is  found  that  an  electric  cur- 
rent flows  from  the  cut  end  to  the  sheath. 

Two  theories  that  may  be  regarded  as  rivals  at 
present  have  been  suggested  as  to  the  nature  of  the 
current.  One  is  that  the  impulse  is  conducted  by 
chemical  changes  within  the  nervous  tissue,  somewhat 
as  the  spark  is  conducted  along  a  fuse.  Against  this 
assumption  must  be  put  the  quickness  with  which' 
the  nerve  recovers  from  fatigue,  and  the  sHght  evidence 
of  chemical  changes,  heat,  etc.  On  this  theory  the  cur- 
rent of  action  would  correspond  to  the  current  that  is 
developed  by  the  chemical  action  in  a  battery.  The 
other  theory,  also  in  favor  at  the  present,  makes  the 
nerve  a  type  of  '  core  conductor  '  in  which  the  central 
nerve  tissue  and  the  sheath  constitute  core  and  sheath. 
The  impulse  corresponds  to  the  movement  of  a  charge 
of  negative  electricity  along  the  fibre.  A  model  con- 
sisting of  a  core  of  platinum  and  a  sheath  of  sodium 
chlorid  solution  shows  phenomena  similar  in  many 
respects  to  the  action  of  the  nerve.  The  current  of 
action,  rate  of  conduction,  and  other  characteristics  of 
the  nervous  action  can  be  reproduced.  Each  theory 
leaves  much  to  be  desired  in  the  explanation  of  the 
details  of  nervous  action.  All  that  can  be  said  is  that 
the  conduction  is  due  to  relatively  slow  progressive 
changes  within  the  nerve  core,  and  I'n.ai  these  changes 


THE   NERVOUS    SYSTEM  —  CORD   AND    BRAIN   STEM      4 1 

are  of  chemical  or  electro-chemical  origin.  Whatever 
the  character  of  this  nervous  impulse,  it  constitutes 
the  essential  activity  of  the  neurone,  and  as  it  travels 
from  sense  organ  to  centre  or  from  centre  to  muscle,  the 
processes  of  sensation  or  of  movement  are  made  possible. 
The  Course  of  the  Impulse.  —  The  specific  activities 
of  the  nervous  system  depend  upon  the  course  that 
the  impulse  takes  through  it.  The  simplest  form  of 
nervous  response  that  an  organism  makes  is  called  the 
reflex.  It  is  the  type  of  all  nervous  action.  The  wink- 
ing of  the  eye,  the  withdrawal  of  the  hand  when  burned, 
are  primarily  reflexes.  The  explanation  of  the  reflex 
is  to  be  found  in  the  presence  of  a  continuous  connection 
of  nerve  tissue,  of  chains  of  neurones,  between  the  sense 
organ  excited  and  the  muscle.  The  simplest  reflex 
involves^  at  least  two  groups  of  neurones,  a  sensory  and 
a  motor.  It  can  be  seen  most  clearly  in  the  spinal 
cord.  If  a  finger  be  pricked,  an  impulse  passes  to  the 
cell  body  of  the  spinal  gangHon,  thence  to  the  motor 
cell ;  its  activity  causes  the  muscles  of  the  arm  to  con- 
tract and  draw  back  the  hand.  That  these  reflexes 
depend  upon  the  nervous  connections  in  the  cord  and 
upon  these  alone  is  evident  from  the  fact  that  they  per- 
sist in  the  lower  animal  after  the  cord  has  been  cut  off 
from  the  brain,  but  cease  if  the  cord  is  destroyed  or  the 
nerves  that  lead  to  or  away  from  it  be  severed.  In  a 
frog,  whose  head  has  been  removed  or  whose  cord  has 
been  cut  in  its  upper  part,  the  reflexes  persist.  Stim- 
ulation of  the  skin  causes  movements  of  the  members. 
Even  a  dog  may  be  kept  alive  after  its  brain  has  been 
removed,  and  this  '  spinal  dog,'  as  it  is  called,  carries 


42 


FUNDAMENTALS   OF  PSYCHOLOGY 


sN 


on  the  reflex  activities  of  the  lower  body  in  a  perfectly 
normal  way.  When  stimulated  on  the  skin  of  one  foot, 
that  foot  will  be  drawn  back.  If  the  intensity  of  the 
stimulation  be  increased,  the  opposite  member  is  moved, 
and  as  the  stimulation  is  still  further  increased  in  in- 
tensity, movements 
up  and  down  the 
trunk  at  many 
different  levels  will 
be  made.  In  the 
frog,  for  example, 
if  a  bit  of  paper  be 
dipped  in  acid  and 
put  upon  the  skin 
of  the  right  thigh, 
the  first  effect  is  to 
bring  the  right  foot 
up  in  an  attempt 
to  wipe  away  the 
paper;  if  that  foot 
be  held,  the  other 
will  be  brought 
across  and  remove 
the  stimulation. 
Reflexes  in  the  Cord.  —  To  understand  these  reflexes 
as  well  as  most  of  the  activities  of  the  lower  part  of  the 
body  it  is  necessary  to  sketch  the  structure  of  the  spinal 
cord.  The  cord  contains  an  inner  mass  of  gray  matter, 
somewhat  like  an  H  in  shape,  surrounded  by  columns  of 
white  matter.  We  may  distinguish  dorsal  and  ventral 
horns  of  the  gray  matter.     The  dorsal  horns  exlenrl 


Fig.  i8.  —  Simple  reflex  connection  in  the 
cord.  C2,  'T '-shaped  cell  in  the  posterior  root 
ganglion;  sN,  sensory  neurone;  h,  dendrite  or 
telodendrion  of  sense  organ  in  skin ;  C  ^  motor 
cell,  connecting  by  axone  n  with  muscle,  M. 
(From  Huber.) 


THE   NERVOUS    SYSTEM  —  CORD   AND   BRAIN    STEM      43 

back  to  receive  axones  from  the  spinal  ganglia.  The 
anterior  horns  contain  large  motor  cells  whose  axones 
send  impulses  to  all  of  the  muscles.  All  acts,  voluntary 
as  well  as  reflex,  are  directly  caused  by  the  excitation  of 
these  cells.  The  columns  of  white  matter  are  divided 
into  three  by  these  horns,  the  dorsal,  the  lateral,  and 
the  anterior.  In  the  simple  ^reflex  the  sensory  impulse 
is  received  by  the  neurones  in  .the  dorsal  root  ganglion, 
thence  is  transmitted  by  their  axones  across  the  gray  to. 
excite  the  anterior  horn  cells,  as  may  be  seen  in 
Figure  i8.  The  sensory  neurones  also  send  collaterals 
to  the  anterior  horn  of  the  opposite  side.  These  col- 
laterals may  connect  directly  with  motor  cells  or  they 
may  come  into  contact  with  the  dendrites  of  inter- 
mediate or  commissural  neurones,  whose  axones  make 
the  connections  with  the  anterior  horn  cells.  The 
points_of  contact-of  axones  and  dendrites^  are  known 
as  the  synapses.  These  offer  resistance  to  the  passage 
of  the  impulse,  and  synapses  differ  in  the  amount  of 
resistance  they  offer.  This  difference  in  resistance 
determines  the  course  of  the  reflex.  Thus  the  synapses 
to  the  motor  neurones  which  excite  the  muscles  of  the 
side  of  the  body  stimulated  are  most  permeable,  and 
in  conr.quence  the  first  and  usual  movement  is  made 
by  the  member  on  the  same  side.  It  is  only  when  the 
stimulus  becomes'  very  strong  that  the  other  member 
moves.  The  neurones  in  the  spinal  gangha  also  send 
collaterals  up  and  down  in  the  cord,  which  connect 
directly  or  through  commissural  neurones  with  the  motor 
neuitones  at  various  levels  (Fig.  19).  These  make 
possible  reflex  excitation  of  groups  of  muscles  above  and 


MTTrn 


•is 

•Si  . 


P  o 


THE   NERVOUS    SYSTEM  —  CORD   AND   BRAIN   STEM      45 

below  the  primary  reflex.  These  cord  reflexes  are  all 
to  be  explained  in  terms  of  the  connections  between 
sensory  and  motor  neurones.  Selection  of  responses 
is  determined  by  the  degree  of  openness  of  the  synapses 
between  different  neurones. 

Tracts  in  the  Cord.  —  In  addition  to  the  reflex  func- 
tions of  the  cord,  it  is  also  an  imnortant  path  of  com- 
mimication  between  the  ^enprfery^jind  the  higher 
structures  of  the  central  nervous'  system,  and  between 
its  own  structures  at  different  levels.  The  conduction 
paths  may  be  divided  into  sensory  or  afferent,  and 
motor  or  efferent.  The  sensory  fibres  all  come,  directly 
or  indirectly,  from  the  dorsal  roots,  the  spinal  ganglia ; 
the  motor  tracts  all  end  in  the  cells  of  the  ventral  horn. 
The  different  tracts  are  to  be  distinguished  in  terms  of 
the  higher  centres  to  which  they  lead  or  from  which  they 
descend.  The  most  important  of  the  higher  centres 
with  which  the  cord  connects  are  the  cerebellum,  which 
receives  ascending  or  sensory  tracts  and  sends  down 
motor  paths  by  way  of  the  red  nucleus ;  the  corpora 
quadrigemina,  from  which  small  tracts  descend  and  to 
which  they  ascend ;  the  thalamus,  to  which  sensory 
fibres  go  on  the  way  to  the  cerebral  cortex;  and  the 
cortex  itself,  the  outer  layers  of  the  cerebrum,  the 
structure  most  closely  connected  with  consciousness. 
From  this  descend  two  tracts,  whose  fibres  carry  vol- 
untary impulses  to  the  muscles  of  the  body.  These 
different  origins  or  goals  give  dift'erent  functions.  Of 
the  afferent  tracts,  the  most  easily  made  out  are  the 
columns  of  Goll  and  Burdach  on  the  dorsal  side.  These 
occupy  most  of  the  region  between  the  dorsal  horns. 


46 


FUNDAMENTALS    OF   PSYCHOLOGY 


The  column  of  Goll  is  nearer  the  centre,  the  column  of 
Burdach  more  lateral.  Each  is  composed  of  fibres  from 
the  spinal  gangHa,  axones  of  neurones  in  the  gangha. 
The  only  difference  is  that  the  more  lateral  fibres  come 
from  parts   of   the  body  on   approximately   the   same 


Ascending  (Centripeial)  Tracts. 
I=Long  fibres  of  the    posterior 
roots. 
11  =Spino-cerebellar  tracts  (a,  dor- 
sal;     b,    ventral  — tract     of 
Gowers). 
IIl=Spmo-thalamic  tract. 


Descending  {Centrifugal)  Tracts. 
l=Cortico-spinal  tracts    (a,  lateral 

pyramid     tract ;    b,    anterior 

pyramid  tract). 
2-5=Subcortico-spinal     tracts     (2, 

rubro-spinal      and      thalamo- 

spinal ;     3,     vestibulo-spinal  ; 

4.  tecto-spinal). 

5.  Descending 
fibres  of  the 
dorsal  column. 


*lorlit. 


ToPOORArHT   OF  THE   LONQ   SpINAL  TEACTS. 

Fig.  2o.  —  Paths  of  Conduction  in  cord.     (From  Bing's  "  Compendium  of 
Regional  Diagnosis."     Published  by  Rebman  Bros.,  New  York.) 


level,  that  have  just  entered  the  cord ;   the  more  central 
have   entered   lower   down   and  been  crowded   toward 
the  centre  by  those  that  come  in  later.     The  column  of  ^ 
Goll  does  jiot' exist  in  the  tower  levels  of  the  cord.     Botr 
groups  of  fibres  end  in  the  medulla  and  there  mak:; 


THE    XERVOUS    SYSTEM  —  CORD   AND    BK\IX    STEM      47 

connections  with  neurones  that  send  impulses  to  the 
thalamus  and  thence  to  the  cortex.  They  are  beheved 
to  earn'  sensations  from  the  muscles.  In  the  same  area 
is  the  so-called  '  comma '  tract,  named  from  its  shape, 
which  consists  of  collaterals  from  entering  neurones 
that  turn  do^mward  to  connect  wdth  motor  cells  lower 
in  the  cord. 

Other  well-marked  afferent  tracts  are  found  on  the 
lateral  border  of  the  cord,  the  cerebellar  tracts.  They 
are  di\dded  into  two,  the  more  dorsal  tract  of  Flechsig 
and  the  more  ventral  of  Gowers.  Both  are  derived 
from  cells  in  the  dorsal  gray  of  the  cord  and  carr}'  im- 
pulses to  the  cerebellum.  Still  another  sensory^  tract 
of  importance  lies  within  Gowers'  tf-act.  It  is  marked 
spino- thalamic  in  Figure  20  and  constitutes  part  of  the 
pathway  from  the  skin  to  the  cortex.  It  is  beheved 
that  sensations  from  the  skin  are  carried  by  axones 
from  the  '  T-'shaped  cells  in  the  spinal  root  ganglia 
into  the  gray  of  the  cord.  There  they  connect  with  a 
second  set  of  neurones  whose  cell-bodies  He  near  the 
spinal  canal.  The  axones  from  these  cells  cross  and  in 
part  go  up  this  spino-thalamic  tract  to  the  thalamus 
and  thence  to  the  cortex.  The  tract  may  also  contain 
some  fibres  leading  to  the  corpora  quadrigemina. 

Motor  Tracts.  —  Of  the  descending  or  motor  fibres 
the  most  important  are  found  in  the  pyramidal  tracts. 
There  are  two  pyramidal  tracts,  the  crossed  and  the 
uncrossed.  The  former,  always  the  larger,  hes  just 
inside  the  Flechsig  tract  and  is  very  close  to  the 
dorsal  horn  of  gray  matter.  The  uncrossed  pyramidal 
tract  Knes  the  ventral  fissure  of  the  cord.     Both  tracts 


48  FUNDAMENTALS   OF  PSYCHOLOGY 

are  composed  of  axones  of  cells  in  the  cerebrum  that 
descend  to  make  connection  with  the  anterior  horn 
cells.  They  carry  the  voluntary  impulses.  The  first 
mentioned  is  composed  of  fibres  that  cross  in  the  medulla, 
the  second  or  anterior  of  fibres  that  have  continued 
down  on  the  same  side  but  cross  in  the  cord  near  the 
level  of  the  cells  with  which  they  connect.  Other 
bundles  descend  from  the  cerebellum.  One  coming  by 
way  of  the  red  nucleus,  the  rubro-spinal  (Fig.  20),  lies 
ventral  to  the  lateral  pyramids;  the  other  is  on  the 
ventral  border.  One  may  also  mention  a  bundle  from 
the  corpora  quadrigemina,  the  tecto-spinal,  on  the 
ventral  border  of  the  anterior  horn.  It  should  be  noted 
that  the  names  appKed  indicate  the  structures  connected : 
the  cortico-spinal  tract  connects  cortex  with  cord,  spino- 
thalamic, cord  with  thalamus,  etc. 

In  addition  to  these  long  bundles  running  from  cells 
at  one  level  to  others  above  and  below,  there  are  numer- 
ous fibres  which  make  possible  the  transfer  of  impulses 
within  the  cord.  These  are  numerous  at  the  borders  of 
the  gray  matter,  but  also  occupy  parts  of  the  white 
area  that  has  been  assigned  no  other  function  in  the 
above  discussion.  It  is  probable  that  some  of  the  sen- 
sations pass  along  these  fibres  on  their  way  to  the  brain. 
They  go  from  neurone  to  neurone,  into  the  central 
gray  and  out  again,  instead  of  taking  the  more  direct 
course  provided  by  the  long  fibres.  It  should  be  added 
that  the  arrangement  of  fibres  is  different  at  different 
levels.  The  pyramidal  tracts,  e.u.,  are  much  larger  in 
the  upper  portions  of  the  cord,  as  some  of  the  fibres  that 
appear  at  the  upper  level  leave  it  to  make  connections 


THE    NERVOUS    SYSTEM  —  CORD   AXD    BR.\IN    STEM       49 

wath  the  ventral  cells.  In  fact,  the  ventral  tract  can- 
not be  made  out  at  all  in  the  lower  regions.  The  rela- 
tive amount  of  white  and  gray  matter  also  varies  at 
different  levels.  The  gray  matter  has  the  greatest 
extent  in  the  lower  lumbar  region  and  in  the  cervical, 


-<'  -^ 


k 


\ 


Fig.  21.  —  Series  of  sections  of  the  cord  to  indicate  difference  in  the  amount 
of  white  and  gray  and  the  relative  size  of  the  cord  at  the  different  levels.  B  is 
a  section  through  the  lumbar  enlargement,  where  the  nerves  of  the  legs  enter  and 
leave;  D,  a  section  through  the  cervical  enlargement  which  supplies  the 
arms.  This  figure,  together  with  figures  23,  24,  25,  and  31,  was  drawn  by 
Mr.  Atwell  of  the  Histological  Laboratory  of  the  University  of  Michigan. 

where  the  large  nerves  for  the  legs  and  arms  enter  and 
emerge.  The  cord  as  a  whole  also  increases  in  cross 
section  from  below  upward  wath  marked  swellings  where 
the  large  nerves  enter.     See  Figure  21. 

Functions  of  the  Brain  Stem.  —  In  the  brain  stem, 
from  the  medulla  upward,  the  structure  of  the  nervous 


50  FUNDAMENTALS  OF  PSYCHOLOGY 

system  becomes  much  more  complicated,  but  the  func- 
tions and  general  arrangements  are  much  the  same. 
We  may  distinguish  three  functions  of  the  structures 
in  the  brain  stem,  i .  Fibres  massed  in  well-defined  tracts 
carry  the  sensory  impressions  upward  and  motor  impulses 
downward  between  cord  and  cerebrum.  2.  Masses  of 
neurones  care  for  the  reflexes  of  the  head  in  very  much 
the  same  way  as  the  cord  for  those  of  the  body. 
Nerves  lead  into  them  from  the  special  sense  organs 
and  from  the  skin  of  the  head,  and  motor  nerves 
lead  out  from  them  to  the  muscles  of  the  head  just  as 
sensory  nerves  lead  into,  and  motor  nerves  go  out  from, 
the  cord.  3.  The  brain  stem  also  makes  wider  inter- 
connections, —  serves  to  combine  large  numbers  of 
sensory  stimuli  from  different  sense  organs  and  to  co- 
ordinate them  in  exciting  muscles  in  widely  distributed 
parts  of  the  bod^v  to  make  harmonious  movements. 
Making  the  different  parts  of  the  body  work  together 
is  the  peculiar  function  of  the  nervous  system.  The 
coordinations  in  the  brain  stem  may  be  wider  than  those 
in  the  cord  and  those  of  the  cerebrum  are  widest  of  all. 
Important  Structures  in  the  Brain  Stem.  —  To  trace 
the  ascending  and  descending  paths  of  impressions,  we 
need  to  distinguish  several  structures  in  the  brain  stem 
that  serve  as  way  stations,  points  where  impulses  are 
transferred  from  the  axone  of  a  lower  neurone  to  the 
dendrites  of  a  neurone  that  carries  them  upward,  or 
where  descending  impulses  are  interrupted  and  trans- 
ferred to  new  neurones.  The  first  Ure  in  the  medulla, 
the  so-called  nuclei  of  Goll  and  Burdach.  These  with 
the  thalamus  are  parts  of  the  pathway  of  sensory  im- 


THE    NERVOUS    SYSTEM  —  CORD   AND    BRAIN    STEM        5 1 


pressions  from  the  trunk  and  limbs.  The  thalamus  is  a 
structure  at  the  base  of  the  cerebrum  which  can  be  seen 
in  a  median  section  of  the  nervous  system  on  the  walls 
of  the  third  ventricle,  or  from  above  in  Figure  22.  Be- 
low it  to  one  side  may  be  seen  the  internal  and  ex- 
ternal genicu- 
late bodies,  and 
below  He  the 
corpora  quadri- 
gemina.  These 
are  both  receiv- 
ing organs  for 
certain  of  the 
fibres  from  eye 
and  ear,  and  will 
be  mentioned 
in  that  connec- 
tion. The  red 
nucleus  Hes  be- 
low the  back  Fig.  22.  — Dorsal  view  of  brain  stem,  /g,  column 
portion  of  the  °^  Goll;  /c,  column  of  Burdach;  n,  anterior,  t,  fx)s- 
tenor  pair  of  corpora  quadrigemina ;  th,  thalamus ; 
thalamus  and  k,  external  and  k'  internal  geniculate  bodies;  s,  epi- 
the  COrDOra  P^^'^^^  (pineal  gland) ;  ps,  pm,  pi,  are  superi<^,  mid- 
^  die,  and  inferior  peduncles  of  the  cerebellum,  which 
quadrigemina  may  itself  be  seen,  in  part  cut  away  and  drawn  to  one 
._,  .         ,       1       ,         side.     (From  Wundt.) 

\\^tmn  the  body 

of  the  brain  stem.  This  is  part  of  the  cerebellar  system, 
a  way  station  from  the  cerebellum  to  the  cord.  A  part 
of  the  cerebellum  can  be  seen  drawn  to  one  side  in 
Figure  22  and  the  pons  is  directly  in  front  of  it.  For 
our  purposes  these  are  most  important  structures  in  the 
brain  stem. 


52 


FUNDAMENTALS   OF  PSYCHOLOGY 


The  Paths  between  Cord  and  Cortex.  —  Impressions 
from  the  sense  organs  of  the  lower  body  may  reach  the 
cortex  by  two  distinct  paths.  The  first,  which  probably 
carries  only  the  impulses  from  the  muscles  and  other 
deeper  lying  tissues,  is  provided  by  the  columns  of  Goll 
and  Burdach.     Axones  of  cell  bodies  in  the  spinal  gan- 


Column  of  Goll 
Column  of 
Eurdach  '' 


Nucleus  of  Goll 


PjTamids 

Fig.  23.  —  Section  through  the  medulla  to  show  the  crossing  of  the  sensory 
fibres,  the  axones  of  cells  in  the  nuclei. of  Goll  and  Burdach.     X  4. 


glia  ascend  by  these  tracts  to  the  nuclei  of  Goll  and 
Burdach.  Here  they  come  into  contact  with  dendrites 
of  other  neurones  whose  axones  cross  and  then  proceed 
up  the  central  portion  of  the  brain  stem  to  the  thalamus. 
Thence  a  third  set  of  neurones  carries  the  impulse  to 
the  cortex.  Sensations  from  the  external  skin  apparently 
travel  by  other  spinal  neurones  whose  axones  enter  the 
central  gray  of  the  cord   and  make  connections  with 


THE    NERVOUS    SYSTEM 


CORD    AND    BRAIX    STEM 


53 


dendrites  of  a  second  neurone  whose  cell  body  lies  near 
the  central  canal.  These  neurones  send  their  axones 
up  the  lateral  column  of  the  opposite  side  to  the  thala- 
mus. The  exact  path  that  is  followed  in  the  lateral 
column  is  not  definitely  agreed  upon.  Some  authors 
believe  that  there  is  a  long  tract  in  the  anterior  portion 


Column  of  Goll 
Column  of 
Burdach 


Fig.  24.  —  Section  of  the  medulla  to  show  the  crossing  of  the  pyramidal  tracts, 
a  section  a  little  below  that  shown  in  Figure  25.     x  4. 


of  the  lateral  column,  the  spino-thalamic  tract  in  Fig- 
ure 20 ;  others  that  the  path  goes  by  way  of  the  lat- 
eral ground  bundle  and  perhaps  may  be  interrupted  at 
different  levels.  The  axone  may  reenter  the  central 
gray  several  times,  connect  w^th  a  new  neurone,  and 
have  that  neurone  continue  the  impulse  upward.  That 
there  is  a  pathway  upward  on  the  side  of  the  cord  oppo- 
site to  that  of  the  sensory-  nerve  stimulated,  and  that 
this  carries  the  cutaneous  sensations,  is  made  very  prob- 
able by  observation  of  pathological  cases.     Both  paths 


54 


FUNDAMENTALS  OF  PSYCHOLOGY 


are  indicated  in  Figure  26.  The  descending  tracts  from 
the  cerebrum  are  the  pyramidal  tracts.  The  fibres  that 
compose  them  are  axones  of  cells  in  the  motor  cortex. 
They  can  be  traced  on  the  anterior  portion  of  the  brain 
stem  through  their  whole  course  except  where  they  inter- 
mingle with  the  fibres  of  the  pons,  as  can  be  seen  in  Fig- 


FiUet 


Pyramida^ 
bundles 


Tranversc  pon- 
tine iibreb 


Fig.  25.  — Section  through  pons.  The  interlacing  of  the  descending  pyram- 
idal tracts,  with  the  cross  fibres  of  the  pons,  mainly  connecting  the  lobes  of  the 
cerebellum,  is  clearly  shown.  Above,  dorsal  to  the  pons,  may  be  seen  the  section 
of  the  fillet,  the  sensory  fibres  ascending  from  the  nuclei  in  the  medulla  to  the 
thalamus.     A  section  of  part  of  the  fifth  nerve  may  also  be  seen. 


ure  25  (a  section  through  the  pons).  In  the  medulla 
part  of  the  fibres  cross,  as  can  be  shown  in  the 
cross  section,  Figure  24.  These  constitute  the  crossed 
pyramidal  tracts  already  noticed  in  the  cord.  The 
remaining  portion,  which  is  usually  smaller  and  may 
not  be  present  at  all,  continues  down  the  anterior  column 
and  crosses  in   the  cord   at   the   level   of  the  anterior 


THE   NERVOUS    SYSTEM.  —  CORD   A^^D    BRAIN    STEM      55 


horn    cells    with 
which  it  is  to  make 
connection.       The 
right  hemisphere  of 
the  cortex  therefore 
always      arouses 
movements    in    the 
left  half  of  the  body, 
and  vice  versa.     The 
course  of   these  de- 
scending fibres  also 
can  be  seen  in  Fig- 
ure 26.     It  may  be 
emphasized  that  two 
neurones  alone  carry 
the    motor    impulse 
from  the   cortex  to 
the  muscle,  while 
three  at  least 
are  concerned 
in  carrying  the 
sensory     im- 
pulse upward. 
Roots     of 
Cranial  Nerves 
and  their  Cen- 
tral Connec- 
tions. —  The 
mid-brain    is 
Hke  the  cord, 
also,    in    its 


Fig.  26.  —  Showing  schematically  the  ascending  and 
descending  tracts  between  cord  and  cortjex,  A,  pyramidal 
tracts ;  B,  motor  cell ;  C,  D,  sensory  cells ;  E,  F,  nuclei  of 
Burdach  and  of  Goll ;  G,  central  sensory  path ;  H,  thal- 
amus. Only  the  sensory  path  by  the  posterior  columns 
is  indicated.  The  arrows  indicate  the  direction  of  the 
impulse.     (From  Cajal.) 


S6 


FUNDAMENTALS   OF  PSYCHOLOGY 


second  set  of  functions,  receiving  sensory  fibres  and 
impressions,  and  sending  out  motor  nerves  and  im- 
pulses.    Unlike  the  continuous  series  of  cells  in  the  cord, 


Fig.  27.  — The  central  connections  of  the  cochlear  branch  of  the  eighth  nerve, 
the  nerve  of  hearing.  The  first  layer  of  neurones  have  their  cell  bodies  in  the 
spiral  ganglia  (VIII  c)  which  correspond  to  the  spinal  root  ganglia  of  the  cord. 
Their  axones  connect  with  a  second  layer  of  neurones  either  in  the  ventral  root  of 
the  eighth  nerve  (na)  or  in  the  tuberculum  acusticum.  The  axones  from  this 
second  layer  of  cells  in  both  nuclei  go  to  the  superior  olives  {os),  some  to  the  one 
on  the  same  side  and  some  to  the  one  on  the  opposite  side.  From  the  olives 
third  neurones  connect  with  a  fourth  layer  of  neurones  with  cells  in  the  nucleus 
lemniscus  lateraUs  (nil)  which  carry  the  impulses  to  the  internal  geniculate  bodies 
(cqtn)  and  thence  by  a  fifth  layer  to  the  temporal  lobe  of  the  cerebrum.  Certain 
of  the  neurones  in  the  olives  send  axones  to  the  inferior  corpora  quadrigemina 
(colliculus  inf.)  where  reflex  connections  are  made  with  motor  roots  of  the  brain 
stem.     (From  Rauber-Kopsch.) 


the  cell  bodies  whose  dendrites  and  axones  constitute 
the  so-called  cranial  nerves  are  grouped  in  isolated  masses 
of  cells  along  the  brain  stem,  the  roots  of  the  several 
nerves.     From  these  roots,  connections  are  made  with 


THE   NERVOUS    SYSTEM . —  CORD   AND   BRAIN    STEM        57 

each  other,  with  coordinating  nuclei,  and  with  cortical 
centres.  The  location  and  connection  of  the  roots 
would  require  more  space  and  the  knowledge  of  more 
details  of  anatomy  than  can  be  given  in  so  brief  a  treat- 
ment. It  may  be  said  in  general  that  there  is  some 
approximation  to  the  arrangement  of  the  spinal  cord 
in  that  the  motor  nerves  frequently  are  anterior  to  the 
ventricles,  while  the  sensory  roots  are  more  lateral  or 
posterior.  These  sensory  and  motor  roots  also  have  con- 
nections with  the  cortex  similar  to  those  of  the  cord. 
We  may  trace  the  course  to  the  cortex  of  some  of  the 
more  important  sensory  nerves  of  the  head.  The  eighth 
nerve,  or  nerve  of  hearing,  consists  of  the  axones  from 
the  cells  in  the  spiral  ganglia  in  the  ear.  These  connect 
with  the  dendrites  of  cells  in  the  root  of  the  eighth 
nerve  at  the  level  of  the  pons ;  from  these,  new  neurones 
carry  the  impulse  to  the  superior  olives  on  both  sides, 
and  thence  by  two  other  neurones  it  goes  forward  to 
the  internal  or  median  geniculate  body,  a  body  near  the 
thalamus,  and  to  the  posterior  corpora  quadrigemina. 
From  the  geniculate  body,  one  set  of  neurones  carries 
the  impression  forward  to  the  cortex  where  hearing 
takes  place.  In  the  posterior  corpora  quadrigemina 
reflex  connections  are  made  and  cared  for. 

The  Optic  and  Cutaneous  Tracts.  —  The  optic  tract 
is  very  similar.  The  axones  from  the  eye  enter  the 
external  geniculate  body  and  possibly  the  pulvinar 
portion  of  the  thalamus,  thence  go  to  the  cortex.  The 
fibres  that  control  the  eye  reflexes  and  the  higher  co- 
ordinations run  directly  to  the  anterior  corpora  quad- 
rigemina.   The  fifth  nerve,  in  part  a  sensory  nerve  for 


58  FUNDAMENTALS   OF  PSYCHOLOGY 

impressions  from  the  skin  and  other  tissues  of  the  head, 
has  its  cells  in  the  Gasserian  ganglion,  which  has  much 
the  same  relation  to  the  brain  stem  that  the  dorsal  root 
ganglia  have  to  the  cord.  Thence  fibres  enter  the  root 
of  the  nerve  and  a  second  neurone  sends  its  axone  to  the 
thalamus,  whence  the  third  neurone  makes  connection 
with  the  cortex.  In  general  the  fibres  of  all  these  nerves 
cross  either  in  the  brain  stem  or,  in  the  case  of  the  eye 
whose  fibres  cross  in  part  only,  in  the  optic  nerve  itself. 
The  fibres  from  the  inner  halves  of  the  retinas  cross, 
and  finally  reach  the  cortex  on  the  opposite  side ;  those 
from  the  outer  halves  go  to  the  cortex  on  the  same 
side.  Corresponding  to  the  pyramidal  fibres  that  de- 
scend to  the  cord,  motor  fibres  also  descend  from  the 
cortex  to  the  roots  of  the  motor  nerves  of  the  head 
and  make  possible  the  voluntary  control  of  the  eyes, 
tongue,  facial  muscles,  etc. 

The  reflex  function  may  be  illustrated  by  the  contrac- 
tion of  the  pupil  in  a  bright  light.  As  was  said  above, 
the  optic  nerve  sends  one  branch  to  the  anterior  corpo 
quadrigemina.  Thence  axones  proceed  to  the  roots  of 
the  third  nerve.  Neurones  there  in  turn  connect  with 
the  ciliary  ganglion  back  of  the  eye,  which  sends  the  im- 
pulse to  the  muscle  in  the  iris.  The  stimulus  of  strong 
light  causes  the  sensory  impression  to  ascend  to  the  cor- 
pora quadrigemina,  whence  it  is  transmitted  by  a  new 
neurone  to  the  motor  root,  thence,  through  at  least  two 
more  neurones,  to  the  muscle  of  the  iris,  whose  contrac- 
tion diminishes  the  diameter  of  the  pupil  (Fig.  30) .  Simi- 
lar reflexes  are  seen  in  sneezing,  which  involves  the  spinal 
cord  as  well  as  the  brain  stem ;  in  making  a  wry  face  at 


THE   NERVOUS    SYSTEM  -  CORD   AXD   BRAIN    STEM 


59 


Corpus 
Ceniculaturti- 
I  at. 


Corpus 
Qeniculatum  lat. 


F,o.  .8.  -The  central  connections  of  the  opfc  nerve.    F^j^,*;--™-," 
the  eye  the  axones  that  form  'heoptx  nerve  exend^^^^^^^  8^^^^^ 

chiasma,  to  the  external  g<="'™lf  <^  .''°*,  *''"'"""  d"n  surface  of  the  occipital 
series  of  neurones  which  carry  the  impulse  to  '^c  ™dian  s^^''«  ^^^or 

lobe.    Other  axones  connect  »2'heP^^^^^^  are  carried 

''^^Z:tZT::.^^:^o^"J^"'^y  the  path/.,  through  .hlch  reaexes  are 

aroused.     (After  Bechterew.) 


6o  FUNDAMENTALS   OF   PSYCHOLOGY 

a  bad  taste,  etc.  In  the  medulla  are  the  reflex  senses 
that  control  respiration,  circulation,  and  other  vital 
functions.  The  details  of  the  paths,  so  far  as  known, 
may  be  obtained  from  any  good  physiology. 

Connections  of  the  Cerebellum.  —  The  third  or 
coordinating  function  is  most  highly  developed  in  the 
cerebellum  and  corpora  quadrigemina.  If  we  consider 
the  connections  of  the  cerebellum,  it  becomes  evident 
that  it  is  closely  connected  with  the  adjustment  of  move- 
ments. To  it,  as  we  have  seen,  go  two  sensory  tracts 
from  the  cord.  To  it  also  go  fibres  from  the  vestibule 
of  the  ear,  the  organ  for  appreciating  the  position  of 
the  body  as  a  whole.  It  receives  fibres  from  the  cortex 
and  fibres  from  the  ocular  tracts.  From  it  go  fibres 
to  the  spinal  cord  by  way  of  the  red  nucleus  in  the  mid- 
brain just  below  the  colliculus  or  corpora  quadrigemina. 
It  also  sends  fibres  to  the  motor  nuclei  of  the  eye  muscles. 
These  make  possible  the  movements  of  the  muscles  of 
»^  the  trunk  and  head. 
/i^b'The  Function  of  the  Cerebellum.  —  The  general 
function  of  the  cerebellum  is  to  coordinate  muscular 
movements,  particularly  those  involved  in  keeping  the 
balance.  The  influence  is  best  evidenced  by  the  defects 
that  appear  when  the  cerebellum  is  injured.  Then  the 
body  is  held  erect  only  with  difficulty,  if  at  all,  the  move- 
ments are  jerky,  the  patient  staggers  when  walking, 
the  gait  is  like  that  of  the  drunken  man.  The  balance 
of  the  body  is  not  adjusted  to  the  movements  of  the 
legs,  the  patient  may  lean  too  far  forward  or  too  far 
back  for  the  immediate  position  of  the  body.  Recent 
work  makes  it  probable  that  certain  parts  of  the  cortex 


Fig.  29.  -The  ascending  or  sensory  connections  of  the  fifth  nerve  The  re- 
lations are  very  similar  to  those  of  the  dorsal  roots  of  the  cord.  The  receiving 
neurones  have^cells  in  the  gangUon  iGan^ion  V],  -^ VXh  f^r  I's'S 
roots,  F5,  which  correspond  to  the  nuclei  of  GoU  and  Burdach  for  the  spinal 
nerves,  whence  the  new  neurones  connect  with  a  third  layer  of  neurones  whose 
ceU  bodies  are  in  the  thalamus  and  which  carry  the  impulse  to  the  cortex. 


62 


FUNDAMENTALS   OF  PSYCHOLOGY 


of  the  cerebellum  take  care  of  definite  parts  of  the  body. 
Streeter  has  established  the  localization  by  tracing  the 
fibres,  Barany  by  a  study  of  the  effects  of  injuries  of  the 
cerebellar  cortex  and  by  direct  stimulation  of  its  sur- 
face. It  is  probable  that  the  sensory  impressions  from 
the  various  organs,  skin,  muscle,  the  vestibules  of  the 

^StmlS!t\     ^^"^  OMtkalmle  h ranch  ofSU.         lory  ciliary  nerues, 

\(J\^  ^^^     -^^   ^^///^. 

jouljiHae. 
SuJoeriorCeroieaL 


Ciliary (^an^lioit.  <^nor7 Ciliary  Tiervcs 


Fig.  30.  —  The  reflex  control  of  the  size  of  the  pupil.  The  impulse  of  dilatation 
takes  the  long  path  from  the  corpora  quadrigemina  down  to  the  cord  and  back 
through  the  cervical  sympathetic,  the  superior  cervical  ganglion,  and  out  through 
a  branch  of  the  fifth  nerve  to  the  iris.  The  impulse  to  contraction  makes  connec- 
tion through  the  third  nerve  with  the  ciliary  ganglion,  thence  to  the  iris.  (From 
Howell's  "  Physiology,"  after  Schultz.) 

ears  and  the  eyes,  which  give  a  knowledge  of  position, 
are  here  united  and  coordinated  and  then  sent  out  to 
the  muscles,  where  they  produce  the  muscular  contrac- 
tions that  keep  the  balanr^^  The  cerebellum  thus 
serves  to  bring  together  the  sensory  impressions  con- 
cerned in  movement,  properly  to  graduate  them,  and 
to   send  out  impulses  which   shall   control   the   lower 


THE   NERVOUS   SYSTEM  —  CORD   AND   BRAIN    STEM        63 

reflexes,  check  some,  increase  others,  and  make  all  work 
together  in  proper  balance. 
y  Functions  of  Corpora  Quadrigemina.  —  From  the 
fact  that  the  corpora  quadrigemina  receive  fibres  from 
skin,  ear,  and  eye  and  have  connections  with  the  motor 
cells  in  the  cord,  as  well  as  w^ith  the  eye  muscles  and 


Fig.  31.  —  Section  of  mid-brain  to  show  position  of  red  nucleus.  The  anterior 
corpora  quadrigemina  and  the  external  geniculate  bodies  can  also  be  seen,  as  can 
the  fibres  of  the  third  nerve,  whose  roots  receive  fibres  from  the  corpora  quad- 
rigemina. In  the  lower  anterior  portion  the  descending  fibres  that  constitute  the 
cerebral  peduncles  may  be  seen.  The  pyramidal  tracts  are  in  the  median  portion 
of  this  structure.     X  2. 


Other  muscles  of  the  head,  it  seems  probable  that  this 
may  be  a  similar  coordinating  center.  In  the  lower 
animals  the  large  development  of  these  organs,  as  com- 
pared with  the  other  region5>  of  the  brain,  together  with 
direct  experiment,  make  it  probable  that  many  of  the 
automatic  movements  are  coordinated  here.  In  man, 
however,   this  lower   centre  of  coordination  has   been 


64  FUNDAMENTALS   OF  PSYCHOLOGY 

largely  overshadowed  in  its  functions  by  the  cerebral 
hemispheres,  so  that  it  plays  a  subordinate  part.  It 
is  the  intermediary  for  reflexes  of  the  eyes,  probably 
for  movements  of  the  head,  but  neither  experiment  nor 
pathology  gives  much  evidence  of  any  peculiar  higher  '  ' 
function. 


CHAPTER  III 

THE   FUNCTIONS   OF  THE   CEREBRUM 

In  the  cerebral  hemispheres  we  come  much  closer  to 
the  problems  that  primarily  concern  psychology.  Here 
we  believe  the  processes  which  accompany  consciousness 
in  all  its  forms  have  their  place,  and  run  their  course. 
But  for  an  understanding  of  the  nervous  operations 
themselves  this  makes  no  difference.  The  structures 
and  their  functions  can  be  best  understood  on  the  analogy 
of  the  lower  parts  of  the  nervous  system.  It  is  in  its 
turn  just  a  mass  of  neurones  with  their  processes,  and  its 
functions  can  be  represented  as  due  to  the  spreading  of 
impulses  along  paths  within  it.  The  problems  that  meet 
us  here  are  those  that  have  met  us  all  the  way  up  to  this 
point.  It  constitutes  part  of  the  highest  and  most 
complicated  path  by  which  sensory  impressions  may  pass 
over  to  the  muscles  and  excite  muscular  contraction. 

The  Parts  of  the  Cerebrum.  —  In  the  cerebrum  may 
be  distinguished  three  sets  of  structures.  On  the  surface 
there  is  a  relatively  thin  layer  of  gray  matter,  a  series 
of  layers  of  neurones  with  connecting  processes,  —  the 
cortex.  This  outer  coat  has  a  much  larger  surface  than  it 
otherwise  would  because  of  the  great  number  of  fissures 
and  folds  that  are  found  on  its  surface.  These  are  much 
more  developed  in  man  than  in  the  animals.  Below  the 
F  6s 


66  FUNDAMENTALS   OF  PSYCHOLOGY 

cortical  gray  the  interior  is  largely  filled  with  white  matter, 
—  masses  of  fibres  that  run  from  the  cortex  downward 
to  the  brain  stem,  from  one  part  of  the  hemisphere  to 
another,  or  from  one  cortex  to  the  other  through  the 
corpus  callosum  and  the  commissures.  At  the  base  of 
the  cerebrum  are  foujid  other  masses  of  gray  matter,  the 
corpora  striata.  These  are  divided  into  a  number  of 
masses  by  the  fibres  that  descend  from  the  cortex  to  the 
lower  brain,  the  corona  radiata.  The  function  of  the 
ganglia  at  the  base  of  the  cerebrum  has  not  been  definitely 
determined.  They  have  connections  with  the  centres  in 
the  brain  stem,  but  relatively  few  with  the  cortex.  It 
has  been  supposed  that  they  had  something  to  do  with 
the  regulation  of  the  temperature  of  the  body,  but  no 
definite  proof  for  the  statement  has  been  given. 

Lobes  of  the  Cerebrum.  —  The  cerebrum  is  divided 
by  the  median  fissure  into  two  hemispheres.  Each 
hemisphere  for  convenience  of  reference  has  been  divided 
into  B.Ye  lobes.  Three  fissures  in  the  cortex  have  been 
selected  as  boundaries.  The  most  prominent  is  the  fissure 
of  Sylvius.  It  is  on  the  side  of  the  cerebrum  and  runs 
backward  and  upward  from  a  point  under  the  skull  on  a 
level  with  the  eyebrows.  Although  the  edges  of  this 
fissure  are  in  contact,  there  is  usually  a  considerable 
hollow  below  the  surface,  and  its  sides  and  bottom  have 
a  considerable  area.  This  surface  is  called  the  island  of 
Reil  and  is  usually  spoken  of  as  one  of  the  five  lobes.  From 
a  point  near  the  middle  of  t^^^^SyivdaiL-fissui^,  a  second 
prominent  fissure  extends  upward  and  a  little  backward 
to  the  median  fissure  and  often  shows  on  the  median 
surface  of  thejiemispheres.     It  never  extends  quite  to 


THE  FUNCTIONS  OF  THE  CEREBRUM        67 

the  fissure  of  Sylvius,  but  is  separated  from  it  by  a  fold 
or  gyre.  The  fissure  itself  is  the  central  fissure,  or 
fissure  of  Rolando.  The  central  fissure  marks  off  the 
frontal  lobe  from  the  parietal  behind  it,  and  the  Sylvian 
fissure  separates  the  frontal  from  the  temporal  lobes. 
The  parietal  lobe  is  bounded  at  the  back  by  the  occipital 
lobe.  The  line  of  division  is  distinct  on  the  median 
surface  of  the  cerebrum,  the  so-called  parieto-occipital 
fissure,  but  no  boundary  is  to  be  noted  on  the  lateral 
surface.  The  Hne  of  demarcation  between  the  parietal 
and  temporal  lobes  is  even  more  difficult  to  describe. 
It  should  be  said  that  the  fissures  and  gyres  are  not  the 
same  on  different  brains.  The  Syhian  fissure  can  be 
recognized  in  every  case,  the  central  in  practically  every 
case,  but  the  others  are  subject  to  considerable  devia- 
tion. These  five  lobes,  the  frontal^temp^ral,  parietal, 
and  occipital,  together  with  the^  island  of  Reil,  are  the 
parts  into  which  we  may  think  of  the  brain  as  divided, 
and  the  two  important  reference  lines  are  the  fissures 
of  Sylvius  and  Rolando.  They  can  all  be  made  out  in 
the  diagram  (Fig^  32). 

WTiile  the  functions  of  the  cerebrum  stand  in  closest 
connection  with  thought  and  with  mental  operations  in 
general,  the  development  of  a  knowledge  of  the  exact 
connection  between  the  parts  of  the  cerebrum  and  mental 
action  has  been  a  matter  of  very  slow  growth.  The 
phrenologists,  Gall  and  Spurzheim,  began  it,  but  their 
methods  were  very  loose  and  their  conclusions  so  much 
mixed  with  speculation  that  hardly  any  progress  was 
made.  After  their  time,  in  the  third  decade  of  the  last 
century,  through  the  work  of  Flourens,  the  opinion  be- 


TA 


o  • 


68 


THE  FUNCTIONS  OF  THE  CEREBRUM        6g 

came  fully  established  that  the  cerebrum  acted  as  a  unit, 
and  no  function  could  be  assigned  to  one  part  rather 
than  another.  It  was  not  until  1867  that  "Broca's 
studies  of  aphasia  gave  a  suggestion  that  each  part  of 
the  cortex  has  a  special  function,  and  led  to  studies  of 
localization.  But  even  in  1890  the  dispute  still  per- 
sisted whether  the  brain  acted  as  a  whole,  or  whether 
different  parts  had  different  functions. 

Methods  of  Studying  Localization  of  Function.  — 
The  methods  that  have  throwTi  light  upon  the  subject 
fall  in  general  under  three  heads,  —  experiment,  observa- 
tion  of  the  effects  of  disease,  and  study^of  the  paths  and 
anatomical  structure  of  the  different  regions.  Experi- 
ments were  early  performed  on  the  lower  animals,  in 
particular  upon  monkeys  and  apes,  whose  brains  most 
nearly  approach  those  of  man  in  structure.  Parts  of  the 
brain  were  extirpated,  and  when  the  animal  had  recovered 
from  the  shock  of  the  operation,  its  movements  were 
studied  to  see  what  change  the  operation  had  made. 
Again  the  brains  of  these  animals  were  exposed  and  the 
cortex  stimulated  by  electric  currents  and  the  resulting 


hemisphere.  In  both  figures  the  motor  areas  are  marked  by  horizontal  shad- 
ing, the  sensory  by  vertical  shading,  while  the  assoqiatory  aceas  are  unshaded., 
The  doubfefejj  or  partially  sensory  and  motor  areas  are  dotted.  5  is  opposite 
the  fissifte  of  Syh-iuss*  R,  above  the  fissure  of  Rolando.  On  the  mesial 
surface  the  parieto-occipital  fissure  is  just  above  the  sTladed  portion  marked  V ; 
M  is  above  the  motor  area'f  C,  above  the  cutfineous  and  kinaesthetic  area-j 
V  indicates  The  \'isual_area :  0  is  below  the  olfactory  j^rea.  The  auditory 
area  is  just  below  the  fissure  of  Sylvius,  ab(>v-e  5",  FA  desigifktes  the  fror^tal-, 
PA,  the  parietal,  and  TA,  "the  temporal  association  areas.  There  is  some 
evidence  that  the  dotted  areas  alDout  the  sensory  and  motor  areas  are  areas  in 
which  particular  associations  are  formed  for  the  corresponding  sense  or  move- 
ments. (The  diagram  embodies  the  results  of  A.  W.  Campbell,  but  has  been 
modified  in  one  or  two  respects  to  agree  with  the  results  of  Flechsig  and 
Cushing.) 


yo  FUNDAMENTALS    OF   PSYCHOLOGY 

movements  were  noted.  In  man,  cases  of  mental  defects, 
whether  sensory  or  motor  in  character,  were  studied 
carefully  and  then  the  brain  of  the  patient  examined 
after  death  and  the  two  series  of  results  brought  into 
connection  with  each  other.  It  was  found,  e.g.,  that  a 
man  who  showed  one  sort  of  difficulty  in  speech  would 
have  lesions  in  one  part  of  the  brain,  a  man  with  another 
sort  of  defect  would  have  another  area  diseased.  Careful 
study  of  many  cases  has  shown  that  there  is  a  close 
relation  between  the  two.  The  anatomical  methods 
have  resulted  in  tracing  paths  of  connection  between 
many  areas,  and  have  shown  some  relations  that  could 
not  be  demonstrated  by  either  of  the  others.  One 
method  of  this  character  that  has  given  noteworthy 
results  was  introduced  by  Flechsig.  He  found  that  the 
different  connecting  paths  in  the  brain  became  medul- 
lated  successively  as  the  nervous  system  developed,  and 
by  a  method  of  staining  brains  at  different  ages,  he  was 
able  to  make  one  path  stand  out  clearly  among  all  of  the 
others  and  to  follow  its  connections  with  ease  and  cer- 
tainty. Even  more  recently  study  of  the  cells,  and  of  the 
arrangement  of  cells  and  fibres  that  make  up  different 
areas,  has  shown  that  areas  which  differ  in  function  dift'er 
also  in  their  finer  structure. 

As  a  result  of  these  methods,  we  feel  assured  that  the 
cortex  is  the  part  in  which  the  final  coordinations  take 
place  and  which  is  most  closely  related  to  consciousness. 
We  may  also  assert  that  the  cortex  constitutes  part  of 
one  of  the  paths,  by  which  sensations  may  be  brought 
into  connections  with  movements.  If  the  brain  is  to 
mediate  sensation  and  movement,   one    might    expect 


THE  FUNCTIONS  OF  THE  CEREBRUM        7 1 

that  certain  parts  of  the  cortex  would  stand  in  closer 
relation  with  the  sensory,  others  with  the  motor  organs. 
This  harmonizes,  too,  with  the  fact  that  fibres  have  been 
traced  to  the  cerebrum  from  sense  organs,  and  from  the 
cerebrum  to  the  motor  cells,  and  so  to  the  muscles.  The 
conjecture  is  confirmed  by  the  results  of  brain  localiza- 
tion. One  may  picture  the  sense  organs  and  muscles 
as  projected  upon  the  cortex.  The  areas  that  receive 
sensory  excitations  and  send  out  motor  impulses  are 
known  as  the  prnj^rtinn  areas.  Other  areas  have  been 
shown  to  be  connected  with  these,  to  have  fibres  leading 
to  and  from  projection  areas.  These  are  known  as 
association  areas. 

The  Motor  Areas.  — The  motor  areas  are  most  defi- 
nitely determined.  They  are  in  the  frontal  lobe  just 
in  front  of  the  central  fissure,  extending  from  near  the 
fissure  of  Sylvius  upward  to  the  median  fissure  and  over 
on  to  the  median  surface.  The  muscles  of  the  head  and 
face  are  represented  upon  the  lower  portion,  the  areas 
for  the  arms,  the  legs,  and  the  trunk  are  found  in  order  as 
one  proceeds  upward.  The  details  can  be  made  out 
with  greater  accuracy  from  the  diagram  than  from  any 
description.  Some  of  the  movements  can  be  localized 
with  great  definiteness.  The  thumb  has  a  separate 
area  for  the  control  of  its  movement,  and  the  same  may 
be  said  of  other  important  organs  and  muscles.  These 
areas  have  been  determined,  in  part  by  a  study  of  the 
paralysis  that  comes  with  disease  and  in  part  by  noting 
the  movements  that  result  from  stimulating  different 
portions  of  the  motor  cortex  in  animals.  Then,  too, 
in  the  motor  areas  are  certain  peculiar  cells,  the  giant 


72  FUNDAMENTALS    OF   PSYCHOLOGY 

pyramidal  cells,  and  these  are  found  to  be  lacking  in  the 
regions  adjoining  in  front  and  behind.  Most  important 
of  all  is  the  fact  that  it  is  possible  to  stimulate  the  motor 
cortex  of  a  man  whose  skull  has  been  opened  for  examina- 
tion. In  a  very  striking  operation  by  Dr.  Gushing,  the 
skull  was  opened  over  a  large  area  during  primary  anaes- 
thesia, then  the  patient  was  permitted  to  return  to 
consciousness  and  the  cortex  stimulated  while  he  was 
in  a  condition  to  report  on  what  happened.  The  results 
obtained  in  this  way  were  sufficient  to  convince  the  world 
of  science  that  the  motor  part  of  the  cortex  is  restricted 
to  the  frontal  lobe  rather  than  extending  backward 
across  the  central  fissure,  as  was  thought  a  few  years 
before. 

The  Sensory  Areas.  —  The  sensory  areas  are  widely 
distributed.  The  sensations  of  touch  are  found  in  the 
parietal  lobe  just  behind  the  central  fissure.  The  definite 
locaKzation  of  parts  of  the  body  has  not  been  determined 
as  it  has  for  movement.  In  fact,  the  opinion  is  still 
held  in  certain  quarters  th^t  movement  sensations  alone, 
i.e.  impressions  received  from  sense  organs  in  rnuscle  and 
tendon,  have  their  seat  in  this  region,  while  the  skin 
senses  proper  are  found  elsewhere,  but  the  upholders  of 
this  theory  assign  them  to  no  definite  place.  Tracing 
paths  and  observation  of  injuries  both  coincide  in  giving 
this  area  to  touch,  whatever  the  final  definition  of  that 
term  may  be.  Auditory  stim_uli  are  received  in  the 
posterior  portion  of  the  temporal  lobe,  in  the  convolution 
adjoining  the  fissure  of  Sylvius,  and  probably  extending 
over  upon  the  wall  of  that  fissure,  the  Island.  Even  more 
accurately  determined  is  the  region  for  vision.     This  is 


THE  FUNCTIONS  OF  THE  CEREBRUM       73 

found  primarily  in  the  calcarine  fissure  on  the  occipital 
portion  of  the  median  surface  of  the  hemispheres.  It 
has  been  located,  on  the  basis  of  examination  of  the 
brains  of  cases  of  cerebral  bUndiiess,  by  tracing  fibres 
from  the  optic  tracts  to  it,  and  by  examination  of  the 
brains  of  indi\iduals  blind  from  birth  or  early  childhood. 
Donaldson  found,  e.g.,  that  the  brain  of  Laura  Bridg* 
man  was  quite  undeveloped  in  this  region.  In  sight,  the 
partial  crossing  of  the  fibres  between  the  eye  and  the 
brain  has  been  very  definitely  made  out.  If  the  right 
occipital  lobe  has  been  injured,  the  patient  is  found  to 
be  bhnd  in  the  right  half  of  both  retinas,  while  the  left 
halves  retain  their  \asion.  The  fovea,  or  central  point 
of  clearest  \'ision^  seems  to  be  represented  on  both  hemi- 
spheres. Apparently,  too,  the  posterior  part  of  this  area 
for  \'ision  receives  impressions  from  the  lower  parts  of 
the  retinas,  while  the  anterior  portion  receives  its  fibres 
from  the  upper  portions.  Smell,  and  particularly 
taste,  are  least  well  localized.  This  is  primarily  due  to 
the  fact  that  a  patient  may  suffer  from  considerable 
defects  in  either  sense  \rithout  great  inconvenience,  and 
in  consequence  is  less  likely  to  complain  and  be  carefully 
studied.  Paths  have  been  traced,  however,  from  the 
olfactory  nerve  to  the  extreme  tip  of  the  temporal  lobe, 
the  hippocamp.  This  region,  too,  is  the  analogue  of  the 
portion  of  the  cerebrum  that  is  well  developed  in  the 
lower  forms  that  show  greater  capacity  for  smell,  so  that 
all  that  we  know  points  to  it  as  the  cortical  seat  of  the 
olfactory  sense.  Taste  is  supposed  to  be  somewhere  in 
the  same  region,  but  the  evidence  is  even  less  certain 
than  for  smell.     Each  of  these  areas  can  be  better  made 


74  FUNDAMENTALS   OF   PSYCHOLOGY 

out  from  the  diagram  (Fig.  32)  than  from  verbal  state- 
ment. 

While  these  more  restricted  areas  are  probably  the 
immediate  receiving  stations  for  the  sensations  in  the 
cortex,  it  is  not  to  be  assumed  that  they  are  the  only 
areas  concerned.  Both  in  sight  and  in  hearing  there  is 
evidence  that  the  areas  about  these  immediate  or  primary 
stations  have  something  to  do  with  the  sense  impressions. 
Injuries  in  the  temporal  lobe  near  the  primary  auditory 
centre  tend  to  decrease  the  efficiency  of  hearing.  Also 
stimulation  of  these  regions  in  animals  calls  out  move- 
ments of  the  ears.  In  the  occipital  region,  either  in  the 
cuneus  or  on  the  lateral  surface,  stimulation  produces 
eye  movements,  and  lesions  are  connected  with  partial 
blindness  or  with  inabiUty  to  interpret  or  perceive 
objects.  The  partial  blindness  may  affect  certain 
qualities  only,  or  may  produce  inability  to  read.  These 
regions  may  be  assumed  to  be  active  in  connecting  and 
elaborating  the  impressions  received  from  the  sense  in 
question,  rather  than  as  serving  as  the  primary  receiving 
centers. 

Association  Areas.  —  As  will  be  seen  from  the  dia- 
grams, these  projection  areas,  taken  even  in  the  wider 
sense  of  the  last  paragraph,  include  relatively  small 
portions  of  the  total  area  of  the  hemispheres.  It  was 
long  a  question  what  the  functions  of  the  other  regions 
might  be.  Flechsig  may  be  said  to  have  found  the 
answer.  By  his  method  of  tracing  the  course  of  develop- 
ing nerve  tracts,  he  showed  that  masses  of  fibres  led 
from  the  projection  areas  to  the  other  regions  of  the 
brain,  —  that  some  were  connected  with  few,  some  with 


THE   FXJNCTIONS   OF   THE   CEREBRUM  75 

many  of  these  regions.  He  inferred  from  this  that  all  of 
the  cortex  not  included  in  the  projection  areas  were 
association  areas.  He  even  attempted  to  assign  specific 
associatory  functions  to  different  areas.  The  posterior 
portions  of  the  parietal  and  temporal  lobes  and  parts  of 
the  occipital  lobe,  or  the  parieto-occipital  association 
areas,  he  assumed  to  have  the  function  of  forming  con- 
nections between  the  neighboring  sense  areas,  and  to  be 
the  seat  of  such  associatory  functions  as  those  involved 
in  the  perception  of  space.  The  frontal  lobe,  so  far  as 
it  is  not  included  in  the  motor  area,  he  makes  the  seat 
of  the  more  complicated  associations  involved  in  reason 
and  judgment.  While  the  specific  functions  of  different 
regions  cannot  be  said  to  be  matters  of  agreement,  it  is 
safe  to  assume  that  the  general  function  of  the  silent  areas 
is  to  make  possible  wide  and  much  varied  associations 
between  the  projection  areas.  There  are  formed  the 
innumerable  connections  between  different  sensations 
and  between  sensations  and  movements  so  important 
for  our  daily  life. 

Functions  of  the  Frontal  Lobes.  —  Specific  evidence 
of  the  dependence  of  associations  upon  the  frontal  lobes 
was  obtained  by  Franz  in  experiments  on  cats  and  apes. 
When  he  taught  his  animals  to  make  various  groups  of 
movements  in  combination,  and  then  removed  part  of 
the  frontal  lobes,  the  recently  formed  associations  were 
destroyed,  but  an  act  that  had  been  well  learned  was  not 
disturbed  by  the  operation.  Animals  that  had  been 
operated  upon  and  had  recovered,  could  learn  new  move- 
ments, and  these  were  again  destroyed  by  a  second 
operation.     It  might  be  argued  that  the  results  noted 


76  FUNDAMENTALS   OF  PSYCHOLOGY 

were  due,  not  to  removal  of  a  particular  area  of  the  brain, 
but  to  the  shock  or  other  general  effects  of  the  operation. 
To  obviate  this  objection  Franz  removed  other  parts  of 
the  brain  in  control  animals  and  found  that  the  opera- 
tion was  without  effect  upon  retention.  He  believes 
that  his  results  have  established  the  close  connection  of 
the  frontal  lobes  with  associations.  Clinical  observation 
in  general  supports  the  view  that  the  frontal  lobes  are 
important  association  regions  and  the  seat  of  compli- 
cated intellectual  operations.  When  these  are  injured, 
the  patient  is  usually  incapable  of  the  higher  mental 
acts,  is  said  to  lose  his  character,  to  be  reduced  to  idiocy 
or  to  a  low  mental  state.  On  the  other  hand,  consider- 
able portions  of  the  frontal  lobe  may  be  lost  without 
any  apparent  effect  upon  the  individual,  so  that  the 
evidence  is  conflicting.  Probably  the  two  sets  of  facts 
are  to  be  brought  into  harmony  on  the  assumption  that 
any  part  of  the  area  may  be  used  for  associations ;  after 
associations  have  been  formed  in  some  one  part  and  that 
part  is  removed,  the  knowledge  is  lost.  When  a  portion 
is  removed  in  which  no  connections  have  been  made, 
no  change  in  the  animal  can  be  noted. 

Aphasia.  —  The  cooperation  of  the  various  areas  of  the 
cerebrum  in  mental  operations  can  be  well  illustrated 
by  a  study  of  the  facts  of  aphasia,  which  we  may  under- 
take as  a  final  review.  This  is  one  of  the  most  familiar 
defects,  and  is  also  illuminating  because  speech  stands 
in  such  close  connection  with  all  of  the  other  mental 
operations.  By  aphasia  is  meant  the  loss  of  speech  due 
to  any  lesion  of  the  brain.  Closely  connected  with  it 
are  agraphia  or  loss  of  ability  to  write,  and  alexia  or  in- 


THE  FUNCTIONS  OF  THE  CEREBRUM       77 

ability  to  read.  They  may  be  treated  together,  as  they 
are  closely  connected  in  use  and  in  the  areas  of  the  brain 
affected,  as  well  as  in  the  principles  of  explanation.  Two 
forms  of  aphasia  are  ordinarily  distinguished.  One  is 
characterized  by  inability  to  produce  the  vocal  move- 
ments in  a  coordinated  fashion,  and  has  been  connected 
since  Broca's  time  with  a  lesion  in  the  third  frontal 
convolution,  an  area  in  front  of  the  immediate  motor 
centres  for  the  muscles  of  the  head  and  throat.  The 
other  is  sensory  aphasia,  first  reported  by  Wernicke  in 
1874.  It  is  more  closely  connected  with  inability  to 
hear,  or  to  think  of  the  word,  a  word  deafness,  and  has 
been  connected  with  injury  to  the  auditory  centre  and 
of  the  immediately  contiguous  areas  of  the  temporal 
lobes. 

Partial  Aphasias.  —  In  addition  to  the  cases  which 
show  complete  loss  of  function  together  with  loss  of 
capacity  to  hear  or  to  anticipate  the  pronunciation  of 
words,  one  must  distinguish  instances  in  which  the 
patient  can  hear  mentally,  can  reproduce  words  to  him- 
self, but  cannot  hear  when  words  are  spoken.  On  the 
other  hand,  there  are  patients  who  can  recall  the  '  feeling ' 
of  words  as  they  are  spoken,  can  have  all  the  antecedents 
of  speech,  but  cannot  speak.  In  these  cases  lesions  have 
been  found  in  the  subcortical  regions  which  affect  the 
projection  fibres  on  the  path  to  the  muscles.  All  the 
cortical  processes  go  on  as  usual  but  the  connections  with 
sense  organ  and  with  muscles  are  broken.  Other  dis- 
tinctions can  be  made  in  sensory  aphasia,  in  particular 
between  injury  of  the  primary  receiving  centre  and  the 
adjoining  elaborating  or  memory  areas.    Thus,  according 


78 


FUNDAMENTALS   OF  PSYCHOLOGY 


to  Adolph  Meyer,  when  the  first  temporal  gyre  on  the 
side  next  the  island  is  injured,  *  word-deafness  '  results. 
In  case  the  lower  portion  of  the  gyre  is  injured,  on  the 
other  hand,  words  are  spoken  hit  or  miss,  what  is  called 
a  '  word-salad  '  is  frequent,  memory  for  words  seems 
disturbed  but  not  destroyed.  Still  another  element 
must  be  added  to  give  a  complete  picture.     Other  than 


Understandln; 
of  writing. 


Fig.  S3.  —  Diagram  of  speech  areas.     (From  Bing,  op.  cii.) 


the  auditory  memories  are  necessary  before  the  words 
can  be  understood  in  their  completeness.  This  has  been 
pictured  by  Wernicke  and  others  as  a  process  of  connect- 
ing the  word  with  a  concept  in  a  concept  centre.  The 
concept  centre  is  probably  too  simple  a  way  of  disposing 
of  the  process,  but  it  is  necessary  to  connect  the  word  or 
sound  with  a  large  number  of  other  experiences  before 


THE  FUNCTIONS  OF  THE  CEREBRUM 


79 


it  is  understood.  With  suitable  reservations  this  may 
be  interpreted  to  mean  that  the  sound  goes  to  an  area 
for  widespread  associations  before  it  is  transferred  to 
the  motor  centre.  If  this  connection  be  injured,  repeti- 
tion of  sounds  heard  is  possible,  but  there  is  no  under- 


Broca'8 
oencre.* 


Fig.  34.  —  Showing  connections  broken  in  cortical  and  subcortical  motor 
aphasia.  In  the  former,  i,  2,  and  3  are  interrupted ;  in  the  latter  only  4.  (From 
Bing,  "  Regional  Diagnosis."     Rebmann  Bros.,  New  York.) 

standing  of  what  is  heard,  and  no  proper  control  of  what 
is  said. 

Five  operations  may  be  thought  of  as  necessary  for 
speech:  i.  the  reception  of  the  sound  in  the  primary 
centre  for  hearing;  2.  its  elaboration  in  the  association 
region  about  the  primary  centre;  3.  more  complete 
elaboration  by  reference  to  other  than  auditory  experi- 


8o  FUNDAMENTALS   OF  PSYCHOLOGY 

ences  (transfer  to  the  hypothetical  concept  centre) ; 
4.  arousal  of  the  coordinated  motor  impulses  in  Broca's 
centre;  5.  conduction  of  these  to  the  separate  motor 
centres,  from  which  the  impulses  are  sent  down  to  the 
muscles.  The  functions  of  areas  4  and  5  are  related  in 
very  much  the  same  way  that  a  higher  coordinating 
region,  such  as  the  cerebellum,  is  related  to  the  activity 
of  a  mere  reflex  centre.  In  the  latter,  a  single  muscle  or 
muscle  group  is  made  to  contract  by  stimulation ;  in  the 
former,  a  large  number  of  sensory  stimuli  are  coordinated 
and  distributed  to  each  of  the  different  motor  centres 
to  cause  just  the  right  amount  of  contraction  in  each 
muscle  at  just  the  right  time,  —  to  marshal  the  different 
component  movements  to  produce  a  satisfactory  total 
result.  The  disappearance  of  any  of  these  centres,  or  of 
the  connections  between  them,  produces  aphasia,  or  in 
less  serious  cases,  paraphasia. 

Other  centres  that  have  been  connected  with  the  speech 
processes  are  the  reading  centre,  which  is  localized  on  the 
lateral  occipital  lobe,  and  the  writing  centre.  The  read- 
ing centre  has  the  same  relation  to  the  primary  visual 
centre  as  has  the  auditory  speech  centre  to  the  primary 
auditory  centre.  It  may  be  imagined  to  be  the  region 
in  which  the  visual  pictures  of  words  are  supplemented 
with  memories  and  thereby  understood.  When  the 
centre  is  injured,  reading  becomes  impossible  or  inac- 
curate. The  writing  centre  is  not  so  generally  accepted 
now  as  it  was  a  decade  ago.  There  have  been  a  few 
cases  of  an  inability  to  write  with  retention  of  ability  to 
speak,  but  it  is  assumed  that  these  were  due  to  injury 
below  the  cortex  or  to  paralysis  of  the  arms  due  to 


THE    FUNCTIONS   OF   THE    CEREBRUII  8 1 

lesions  in  the  cortical  area  for  the  control  of  arm  move- 
ments, rather  than  to  the  destruction  of  a  single  centre 
for  the  coordination  of  the  specific  movements  involved 
in  writing,  similar  to  Broca's  centre  for  speech.  It  should 
be  said,  in  lea\ing  the  discussion  of  speech  functions, 
that  the  cases  are  by  no  means  so  clear  cut  as  one  might 
\vi5h.  There  is  much  contradiction  and  confusion  in  the 
observation  made  which  is  only  partially  harmonized 
in  such  a  schematism  as  that  given  above.  Still  this 
may  be  regarded  as  a  simple  picture  of  what  takes 
place. 

The  Left  Cerebrum  Dominant.  —  It  should  be  empha- 
sized that,  in  right-handed  indi\'i duals  at  least,  the  speech 
functions  have  their  seat  in  one  hemisphere  only,  the 
left.  In  cases  of  injury  to  the  right  brain  in  what  cor- 
responds to  Broca's  or  Wernicke's  centres,  speech  suffers 
no  injury.  Apparently  this  is  only  one  phase  of  the 
general  fact  that  in  right-handed  individuals  the  left 
hemisphere  cares  for  the  more  important  and  delicate 
coordinations,  while,  with  exceptions,  the  right  hemi- 
sphere dominates  in  the  left-handed  individuals.  If  an 
injury  be  done  to  the  right  hemisphere  in  the  third 
frontal  convolution  but  the  primary  motor  centres  be 
not  injured,  the  speech  functions  are  not  disturbed. 
Similarly  when  the  motor  region  in  the  left  hemisphere 
is  injured  but  the  right  is  unaffected,  it  is  found  that  the 
left  hand  is  rendered  incapable  of  delicate  movements, 
although  there  is  no  sign  of  paralysis  and  the  coarser 
movements  are  unaffected.  Liepmann  found  one  case 
in  which  both  hemispheres  were  normal,  but  where  there 
was  a  lesion  in  the  corpus  callosum,  the  mass  of  fibres 


82 


FUNDAMENTALS   OF  PSYCHOLOGY 


which  connects  one  cortex  with  the  other  (Fig.  35). 
In  this  case,  the  right  hand  was  normal,  the  left  what  is 
called  apraxic,  —  that  is,  delicate  movements  could  not  be 
carried  through  with  accuracy.    These  cases  indicate 


Hanoi 


zur 
KandL 


Fig.  35.  —  Showing  the  lesions  that  might  break  the  connections  between 
the  left  and  right  hemispheres  and  so  produce  apraxia  of  the  left  hand.  If  the 
lesion  is  at  i,  the  right  hand  will  be  paralyzfed  as  well,  if  at  2  or  3  only  apraxia 
of  the  left  hand  is  caused.     (From  Bing,  op.  cit.) 

that  the  highest  coordinations,  whether  in  speech  or  in 
manual  exercises,  are  accomplished  in  the  left  hemi- 
sphere. It  has  been  suggested  that  right-handedness  is 
really  left-brainedness,  and  vice  versa. 


THE  FUNCTIONS  OF  THE  CEREBRUM        83 

Restitution  of  Function.  —  Interesting,  too,  in  this 
connection  is  the  fact  of  restitution  of  function  in  cases 
of  cerebral  lesions.  Not  infrequently  an  aphasic  will 
show  marked  improvement,  sometimes  almost  complete 
recovery,  with  no  betterment  of  the  lesion.  In  surgical 
cases  the  patient  will  frequently  show  considerable 
paralysis  immediately  after  part  of  the  cortex  has  been 
removed,  but  -svith  the  passage  of  time  his  movements  wiU 
become  normal  again.  Various  speculations  have  been 
indulged  in  to  explain  this  phenomenon,  such  as  that  the 
function  is  taken  over  by  the  other  hemisphere,  that  the 
paralysis  is  due  to  shock,  and  when  that  passes,  the  old 
structures  regain  their  acti^ities,  or  in  general  that  some 
other  part  of  the  nervous  system  can  take  over  the  work. 
No  one  of  these  theories  has  received  general  acceptance, 
nor  can  any  be  said  to  be  altogether  satisfactory,  but 
it  is  important  in  several  connections  to  note  that  there 
is  a  considerable  degree  of  flexibility  in  function  exhibited 
by  many  of  the  nervous  structures.  Surgeons  have 
joined  part  of  the  central  end  of  a  flexor  nerve  to  the 
peripheral  end  of  an  injured  extensor  nerve  and,  when 
regeneration  has  taken  place,  the  nerve  and  its  central 
connections  perform  the  new  function  without  a  hitch. 
In  cases  of  destruction  of  one  path  through  the  cord,  as  in 
infantile  paralysis,  it  is  found  that  new  paths  will  develop 
and  the  paralysis  disappear  in  time,  pro\dded  only  that 
the  muscle  be  kept  from  degenerating  while  new  paths 
are  being  developed.  Vicarious  functioning,  replacing 
of  one  structure  by  others,  seems  to  be  a  fairly  general 
law  of  nerv^ous  action,  although  much  remains  to  be 
learned  of  the  limits  and  details  of  the  process. 


84  FUNDAMENTALS   OF  PSYCHOLOGY 

Resume  of  Nervous  Functions.  —  In  brief,  then,  we 
see  that  in  the  nervous  system,  the  action  of  all  parts 
depends  upon  a  transfer  of  sensory  impulse  to  motor 
neurones,  and  the  consequent  excitation  of  muscular 
movements.  There  are  three  levels  in  the  nervous 
system  at  which  the  transfer  from  sensory  to  motor  organs 
may  take  place  :  i .  at  the  level  of  the  simple  reflex  in  the 
cord  or  brain  stem ;  2.  in  the  higher  coordination  centres 
in  the  brain  stem,  the  cerebellum,  and  the  corpora  quadri- 
gemina;  and  3.  in  the  cortex.  As  one  passes  to  the 
higher  levels,  the  number  of  sensory  impulses  concerned 
in  guiding  movements  becomes  greater,  and  in  conse- 
quence the  movements  become  more  accurately  adjusted 
to  the  environment,  to  the  circumstances  of  the  moment. 
In  the  cortex,  the  association  centres  provide  regions 
where  all  sense  impressions  may  be  brought  into  connec- 
tion with  each  other  and  with  retained  impressions,  and 
where  all  combine  to  control  movements.  Action  is  in 
the  Hght  of  past  as  well  as  of  present  experience.  In 
consequence,  the  highest  forms  of  adaptation  are  possible. 
Aside,  however,  from  the  increasing  complexity  of  inter- 
action, the  highest  and  the  lowest  forms  of  nervous 
action  follow  the  same  laws.  The  control  of  the  path 
taken  by  the  impulses  through  its  structures  may  also 
be  explained  on  the  same  general  principles. 

Perhaps  the  best  notion  of  these  principles  is  given 
by  a  theory  elaborated  by  Professor  Sherrington.  This 
regards  the  course  of  an  impression  through  the  nervous 
system  as  determined  by  the  ease  or  difficulty  with  which 
nerve  processes  may  pass  from  one  neurone  or  nerve 
element  to  another,  the  amount  of  resistance  at  the 


THE   FUNCTIONS    OF   THE    CEREBRUM 


8s 


synapses.  This  has  already  been  briefly  mentioned  in 
the  preceding  chapter.  The  great  number  of  synapses 
that  may  be  crossed  can  be  seen  in  Figure  36,  which 
shows  the  large  number  of  collaterals  and  end  brushes 
of  a  single  neurone  from  the  cerebellum  of  a  rat. 

The  final  explanation  of  why  one  synapse  should  be 
more  permeable  than  another,  and  why  the  same  s^Tiapse 


Fig.  36.  —  The  numerous  points  of  connection  of  a  neurone  from  the 
cerebellum  of  a  rat.     (Cajal.) 

should  be  more  easily  crossed  at  one  time  than  at  an- 
other, has  been  the  subject  of  much  discussion  and  is 
not  completely  agreed  upon  as  yet.  The  earliest  and 
simplest  explanation  grew  out  of  the  picture  of  the  ner- 
vous system  as  a  colony  of  individual  cells  each  like 
an  amoeba,  which  could  control  in  some  degree  the 
extension  and  withdrawing  of  processes.  Just  as  a 
group  of  amoebae  that  happened  to  be  in  contact  might 
send  out  pseudopods  and  touch  each  other  at  different 
times  and  places,  so  the  neurones  might  on  occasion 


86  FUNDAMENTALS    OF   PSYCHOLOGY 

send  out  or  increase  the  length  of  the  dendrites  until 
they  came  into  contact  with  the  end  brushes  of  the 
neighboring  axones.  It  was  further  assumed  that  when 
physical  contact  was  present  between  the  neurones,  a 
nervous  impulse  might  pass,  while  at  other  times  the 
path  was  blocked.  Some  authorities  asserted  that  the 
dendrites  were  shorter  in  animals  killed  by  an  anaesthetic 
than  in  others.  The  theory  was  used  to  explain  sleep  as 
due  to  a  blocking  of  all  the  pathways  to  consciousness,  g 
Later  consideration  has  led  to  the  abandonment  of  the 
theory.  It  would  make  all  action  of  the  nervous  system 
depend  upon  chance  activities  or  arbitrary  activities  in 
the  separate  cells,  rather  than  upon  the  way  they  were 
affected  from  without,  or  by  other  cells.  Sleep  might 
be  satisfactorily  explained,  but  on  the  theory  it  would 
never  be  possible  to  waken  the  individual  until  the  neu-  m 
rones  were  ready  to  put  out  their  dendrites  again. 

Sherrington  is  convinced  from  a  careful  study  of  the 
times  required  for  the  reflex  movements  under  different 
conditions,  that  we  must  think  of  the  synapse  as  con- 
stituted by  continuous  tissue,  but  also  as  containing  a 
membrane  of  some  sort  which  offers  a  resistance  to  the 
passage  of  the  impulse,  and  that  the  degree  of  resistance 
is  determined  by  the  degree  of  permeability  of  the 
membrane.  The  neurones  would  always  be  in  contact, 
the  reflex  path  is  always  continuous,  but  the  impulse 
is  impeded  at  the  point  of  contact  between  axone  and 
dendrite. 

If  we  may  be  satisfied  with  the  theory,  we  still  'have 
to  ask  why  one  synapse  should  be  more  permeable  than 
another.     In  the  lower  centres  it  may  be  assumed  that 


THE  FUNCTIONS  OF  THE  CEREBRUM        87 

the  openness  of  certain  synapses  and  the  closed  condi- 
tions of  others  is  inherited,  that  it  either  is  present  at 
birth  or  appears  soon  after  as  a  result  of  the  inherited 
predisposition.  Few  reflexes  are  perfect  at  first,  —  they 
improve  for  days  or  even  weeks  in  the  higher  animals. 
At  first  the  child  does  not  accurately  touch  a  point 
stimulated  although  there  is  usually  some  indefinite 
waving  of  the  arms.  Many  of  the  more  complicated 
reflexes  and  instincts  make  their  appearance  late,  al- 
though probably  the  development  comes  in  large  part 
as  a  result  of  growth  rather  than  of  learning.  The  paths 
open  at  birth  determine  a  relatively  larger  proportion 
of  the  total  number  of  paths  in  the  cord  and  mid- 
brain than  in  the  cortex,  but  probably  form  a  large 
number  of  the  total  connections  even  in  the  adult  cortex, 
and  the  general  lines  of  connection  are  pretty  well  laid 
down  there. 

Habit  a  Change  in  the  Synapse.  —  The  connections 
that  develop  in  the  life  of  the  individual  as  a  result  of 
learning  are  due  to  changes  that  take  place  in  the  charac- 
ter of  the  membrane.  What  this  change  is  is  not  deter- 
mined and  cannot  be,  so  long  as  we  do  not  know  what 
the  nature  of  the  opposition  in  the  membrane  may  be. 
We  do  know  that  the  more  often  two  neurones  are  excited 
together  or  in  immediate  succession,  the  greater  is  the 
likelihood  that  the  activity  of  one  will  extend  to  the  other. 
All  learning,  whether  in  the  formation  of  habits  or  in 
the  connection  of  sensory  impressions  in  sensory  learning, 
is  due  to  this  reduced  resistance.  The  laws  that  govern 
the  reduction  of  resistance  from  use  are  known  in  some 
degree  from  the  observations  of  the  behavior  of  the 


SS  FUNDAMENTALS  OF  PSYCHOLOGY 

4 

organism,  but  our  theory  takes  us  only  to  the  point  where 
we  may  say  that  learning  is  due  to  some  sort  of  reduction 
in  the  resistance  offered  by  the  synapse  to  the  passage 
of  the  nervous  impulse. 

Our  picture  of  the  action  of  the  cortex,  as  of  the  cord, 
is  that  all  is  determined  by  the  openness  of  paths,  by  the 
synapses.  The  passage  of  the  impulse  from  sense  organ 
to  muscle  is,  as  has  been  emphasized  repeatedly,  the 
explanation  of  all  function,  whether  in  cord  or  in  cere- 
brum. The  difference  between  the  two  is  that  there 
are  more  open  paths  in  the  latter  over  which  any  impulse 
may  pass  and  that  for  the  most  part  these  paths  have 
been  opened  by  use,  by  the  earlier  acti\'ities  of  the  organ- 
ism. It  should  also  be  emphasized  that  many  dift'erent 
stimuli  cooperate  in  producing  the  activities  that  result 
from  the  action  of  the  cortex,  many  more  than  act  to- 
gether in  any  of  the  lower  centres  or  organs.  The 
cooperation  is  made  possible  by  the  fact  that  many  of  the 
paths  have  common  parts  ;  in  fact,  that  the  motor  part  of 
the  path  is  common  to  very  many  different  acts.  In  the 
majority  of  cases  the  same  muscles,  and  even  the  same 
groups  of  muscles,  are  used.  The  excitation  of  the 
motor  path  may  be  aroused  by  a  number  of  sensory  im- 
pressions, and  the  various  impressions  may  be  thought 
of  as  cooperating  in  the  final  action.  What  is  even  more 
important  in  this  connection  is  that  each  sensory  im- 
pression may  be  connected  with  several  motor  or  inter- 
mediate neurones,  and  the  action  which  results  when 
the  sensory  impression  is  received  must  depend  upon  the 
openness  of  the  various  synapses,  of  paths  leading  to  the 
possible   motor   organs   that  may   be   excited.     Wliere 


THE   FUXCTIOXS    OF   TEIE    CEREBRUM  89 

very  large  numbers  of  stimuli  are  presenting  themselves 
at  every  moment,  there  must  be  a  large  amount  of  co- 
ordination, of  reciprocal  influence,  to  determine  which 
of  the  possible  movements  is  actually  made.  The 
strongest  impression  and  the  one  whose  neurone  has  the 
most  open  synapses  between  it  and  the  motor  neurones 
\vill  determine  the  action. 

facilitation  and  Inhibition.  —  In  addition  to  this  mere 
openness  of  paths  and  the  greater  strength  of  the  impres- 
sions, coordination  seems  to  imply  mutual  interaction 
between  the  neurones  of  one  path  and  those  of  another. 
Sherrington  and  others  have  demonstrated  two  forms 
in  which  one  path  or  series  of  neurones  may  act  upon 
others.  One,  the  more  direct,  is  some  process  of  making 
easier  the  path  for  one  response  by  another  set  of  neurones 
active  at  the  same  time.  This  is  very  common.  It  may 
be  illustrated  very  easily  by  the  knee-jei-k.  You  are 
familiar  ^vith  the  fact  that  if  you  strike  sharply  the  tendon 
below  the  knee-cap  when  one  leg  is  crossed  over  the  other, 
the  foot  vvdll  give  a  kick.  It  has  been  shown  that  the 
kick  \\ill  be  much  stronger  if  the  hands  are  clenched  at 
the  time  the  blow  is  given.  The  clenching  of  itself  would 
not  produce  the  kick,  but  it  prepares  the  way  for,  or 
facilitates,  the  response  when  the  blow  is  given.  This 
may  be  pictured  as  a  preparatory  reduction  of  the  resist- 
ance of  the  synapse  which  makes  the  impulse  pass  more 
easily,  and  hence  with  greater  intensity,  when  the  suit- 
able stimulus  is  applied.  More  striking  is  the  second 
fact  of  inhibition.  Certain  paths  when  active  prevent 
the  action  of  others,  or  reduce  their  HabiHty  to  response. 
Sherrington  has  demonstrated  this  phenomenon  in  the 


90  FUNDAMENTALS  OF  PSYCHOLOGY 

case  of  many  reflexes,  such,  for  example,  as  the  general 
reduction  of  the  strength  of  the  reflexes  of  the  cord  when 
it  is  in  connection  with  the  cerebrum.  After  the  cere- 
brum has  been  removed  and  the  animal  has  recovered 
from  the  shock  of  the  operation,  all  reflexes  are  exagger- 
ated, a  fact  explained  on  the  assumption  that  in  the 
normal  animal  all  lower  reflexes  are  inhibited  by  the 
higher  centres.  More  interesting  for  our  immediate 
purpose  is  the  fact,  fully  established  by  Sherrington  and 
Hering,  that  the  flexor  and  extensor  centres  in  the  cortex 
mutually  inhibit  each  other.  They  removed  the  flexor 
muscles  of  a  member,  placed  the  animal  in  such  a  posi- 
tion that  there  was  a  tendency  for  flexion,  —  it  was  sup- 
ported only  by  the  extensor  muscles,  e.g.,  —  and  noted 
that  the  member  was  lowered  when  the  flexor  centre  was 
stimulated.  This  they  explained  by  an  inhibition  of  the 
cortical  centre  of  the  extensor  muscle  from  the  flexor 
centre  which  reduced  the  tonus  of  the  extensor,  and  so 
permitted  the  member  to  be  flexed.  This  was  also 
demonstrated  on  the  antagonistic  eye-muscles.  If  the 
internal  muscle  of  the  eye  were  severed  and  the  cortical 
centre  for  that  muscle  were  stimulated,  the  eye  would 
turn  as  it  would  if  the  centre  for  the  internal  muscle  had 
been  stimulated.  This  mutual  checking  of  antagonistic 
movements  prevents  any  possibility  of  interference 
between  groups  of  muscles  in  voluntary  action,  —  makes 
impossible  any  pulling  against  each  other  that  might 
come  were  no  such  interrelation  present.  Inhibition  is 
assumed  by  Sherrington  to  be  due  to  the  action  of  one 
set  of  neurones  upon  a  synapse  somewhere  along  the 
other  path  of  discharge.     The  activity  of  that  set  of 


THE  FUNCTIONS  OF  THE  CEREBRUM        9 1 

neurones,  in  some  way  as  yet  unknown,  makes  the 
membrane  at  the  synapse  much  less  permeable,  and  so 
prevents  the  discharge  of  the  impulse  across  it. 

These  processes  of  facilitation  and  inhibition  are 
quite  as  essential  to  the  interaction  of  various  stimuli 
in  the  cortex,  as  well  as  in  the  lower  centres.  As  will  be 
seen  from  time  to  time  in  considering  the  mental  pro- 
cesses, the  most  important  and  striking  fact  is  the  wide 
interaction  of  mental  processes.  It  is  seldom  that  an 
act  or  a  thought  is  controlled  merely  by  a  single  stimulus 
or  even  by  the  stimuli  that  are  being  received  at  the 
moment  of  action.  The  laws  of  facihtation  and  inhibi- 
tion of  one  set  of  cortical  acti\ities  by  others  that  are 
going  on  simultaneously  in  other  paths  and  in  other 
areas,  are  needed  if  we  are  to  obtain  any  accurate  picture 
of  cortical  action.  The  details  of  this  interaction  can  be 
left  to  the  particular  fields  in  which  they  are  to  be  applied. 

The  relation  of  consciousness  to  the  total  action  of  the 
brain  may  be  briefly  mentioned.  On  the  physical  side, 
the  action  of  the  nervous  system  may  be  thought  of  as 
the  passage  of  chemical  or  electrical  changes  or  processes 
through  its  various  structures.  These  are  present  not 
at  a  single  place  but  everywhere  throughout  the  mass  of 
neurones,  —  hundreds,  if  not  thousands,  of  separate 
sensor-motor  arcs  are  carrying  impulses  at  the  same 
time  —  for  the  muscles  not  only  are  moved  by  nerve 
impulses  when  they  move,  but  are  also  kept  in  slight  or 
tonic  contraction  by  the  constant  action  of  the  neurones. 
But  of  all  these  activities,  only  relatively  few,  perhaps 
not  more  than  one  group  at  a  time,  are  accompanied  by 
clear  consciousness.     The  others  do  their  work  without 


9^  FUNDAMENTALS  OF  PSYCHOLOGY 

being  noticed.  If  they  contribute  at  all  to  consciousness, 
it  is  only  by  modifying  the  total  mass  in  some  slight 
degree.  They  are  silent  servants,  —  their  addition  is 
lost  in  the  complex.  The  general  rule  is  that  conscious- 
ness attaches  to  activities  which  are  performed  for  the 
first  time,  or  which  offer  special  difficulties.  As  move- 
ments are  repeated,  they  gradually  cease  to  attract  atten- 
tion, and  usually  by  the  time  they  can  be  carried  out 
effectively,  only  the  intention  or  the  first  beginnings  of 
the  act  are  conscious.  There  is  no  evidence,  however, 
that  the  impulse  follows  any  distinctively  new  path 
after  it  ceases  to  be  conscious,  that  a  voluntary  act  is 
first  carried  out  by  the  cortex,  e.g.,  and  then  by  the  lower 
centres.  It  seems  probable  rather  that  consciousness 
drops  away  as  the  impulse  crosses  the  synapses  more 
easily.  The  paths  followed  are  still  the  same  when  the 
action  becomes  easy,  but  we  are  not  aware  of  the  activity. 
The  Relation  of  Body  and  Mind.  —  Much  of  modern 
psychology  since  Descartes  has  dealt  with  the  problem  of 
how  the  mental  processes  are  related  to  these  nervous 
processes  we  have  just  been  discussing.  The  problem 
originated  from  the  fact  that  behavior  may  be  studied  in 
two  ways,  from  without  and  from  within.  When  one 
attempts  to  study  man  with  the  scalpel  and  the  instru- 
ments of  the  physiologist,  he  deals  always  with  the 
physical  man,  with  nerve  and  nerve  cell,  with  white 
matter  and  gray  matter,  but  he  never  finds  any  trace  of 
sensation,  of  the  inner  experience.  On  the  other  hand, 
when  one  studies  the  mental  states  and  devotes  oneself 
to  what  can  be  seen  in  one's  own  consciousness,  alone, 
one  never  finds  any  immediate  evidence  of  nerve  cells. 


THE   FUNCTIONS    OF    THE    CEREBRIBI  93 

For  the  most  part  investigators  have  preferred  one  or  the 
other  of  these  approaches  to  the  facts  of  mind,  —  few 
men  have  given  due  credit  to  both.  Even  where  each 
attracts  the  interest  of  the  same  man,  it  is  seldom  that 
both  are  combined  in  a  single  statement,  or  completely 
harmonized.  More  frequently  one  is  entirely  subordi- 
nated and  to  all  intents  and  purposes  we  are  given  an 
explanation  that  is  either  completely  materiaKstic  or 
spiritualistic.  Most  writers  compromise,  and  while 
they  subordinate  one  of  the  two  series  they  still  leave  it 
as  an  accompaniment  but  without  real  force,  a  sort  of 
ghost  of  mind  or  of  body  which  merely  follows  the  ac- 
ti\ity  of  the  other  but  has  no  influence  upon  it. 

Very  generally,  at  present,  the  two  lines  of  approach 
are  recognized  and  both  of  the  resulting  series  of  experi- 
ences are  accepted  as  real.  The  problem  that  makes 
trouble  is  how  to  think  of  the  relation  between  them. 
Two  theories  of  what  this  relation  is  may  be  recognized. 
One  takes  the  natural  attitude  that  the  two  series 
interact  as  do  series  of  physical  events;  that  when  a 
sense  impression  is  received,  it  is  transmitted  to  the  brain 
by  the  paths  we  have  indicated,  and  that  in  the  brain  it 
in  some  way  gives  rise  to  the  incorporeal  process  we  know 
as  sensation  or  knowledge,  in  the  same  way  that  the 
\ibration  of  a  sounding  body  may  give  rise  to  vibrations 
in  the  air.  Similarly,  it  is  assumed  on  the  other  side  that 
voluntary  processes  may  produce  changes  in  the  nervous 
system  and  so  in  the  physical  universe,  just  as  simply 
as  do  physical  forces  in  other  physical  objects.  This 
theory  of  the  relation  of  body  and  mind  is  known  as 
interactionism. 


94  FUNDAMENTALS    OF   PSYCHOLOGY 

Another  theory  equally  current  at  present  is  known  as 
psycho-physical  parallelism.  It  is  an  expression  of  the 
conservatism  of  modern  thinkers  in  refusing  to  assert  any 
particular  sort  of  relation  between  body  and  mind.  The 
mental  series  is  assumed  to  constitute  one  train  of  events 
which  can  be  explained  in  terms  of  earlier  mental  events ; 
the  physical  series,  the  changes  in  nervous  elements, 
is  made  entirely  distinct,  and  it  is  assumed  that  they 
can  be  completely  explained  in  terms  of  the  antecedent 
physiological  processes.  The  relation  between  the  two 
series  either  is  left  unexplained  or  it  is  said  positively 
that  there  is  no  interaction  between  them.  When  one 
recalls  an  event,  e.g.,  one  would  run  through  the  series 
of  ideas  until  the  proper  associate  presented  itself. 
On  the  physical  side,  the  series  in  recall  would  depend 
upon  the  connections  that  had  been  estabHshed  between 
"neurones  in  different  sensory  areas  of  the  cortex,  and  the 
action  resulting  from  the  recall  would  be  due  to  the 
transfer  of  some  nervous  excitation  from  a  sensory  area 
to  the  corresponding  motor  area.  When  it  is  asked, 
however,  how  it  comes  that  the  nervous  processes  are 
always  accompanied  by  the  mental  states,  one  of  two 
answers  is  made.  The  more  extreme  men  assert  that 
there  is  no  present  connection  between  the  two  series  of 
events.  Each  runs  its  own  course  because  of  some  of 
the  antecedent  events  within  itself,  but  nothing  that 
happens  in  the  other  can  influence  it.  The  two  are  kept 
together  because  they  go  at  the  same  rate,  rather  than 
because  of  any  cross  connection  between  them.  Mem- 
bers of  the  other  school  are  less  dogmatic  in  the  negative. 
They  assert  merely  that  they  do  not  know  the  nature  of 


THE  FUNCTIONS  OF  THE  CEREBRUM       95 

the  connection,  not  that  there  is  no  connection  between 
the  two  series. 

The  evidence  adduced  by  the  upholders  of  each  theory 
is  largely  negative.     The  negative  considerations  upon 
which  parallelism  is  based  are  the  fact  that  one  never 
can  appreciate  both  series  at  the  same  time,  can  see 
nothing  pass,  and  that  the  two  series  of  events  are  not  at 
all  comparable.     One  cannot  think  of  a  thought  moving 
a  stone,  or,  in  Clifford's  term,  it  seems  absurd  to  assert 
that  two  cars  are  coupled  by  the  bond  of  affection  between 
guide  and  guard,  and   to  speak  of   a  thought  making 
any  change  in  nerve  cells  is  on  exactly  that  level.     At 
times  the  argument  is  given  a  more  formal  turn  in  the 
assertion  that  to  assume  interaction  is  in  violation  of 
the   doctrine  of    the  conservation    of    energy.     If    the 
physical  series  is  to  be  regarded  as  a  closed  system  of 
energy,  it  can  neither  give  off  energy  to  the  mental  states 
as  is  required  if  sensations  are  to  be  caused,  nor  can  it 
be  changed  by  mental  states,  as  would  be  necessary  if 
human  volitions  were  to  exert  an  influence  upon  the 
nerve  cells.     In  passing  upon  these  objections,  one  must 
remember,  however,  that  the  doctrine  of  conservation  is 
itseh  only  a  principle  that  has  been  set  up  for  conven- 
ience, and  must  be  given  up  if  it  should  cease  to  har- 
monize with  facts,  and  also  that  it  may  be  possible  in 
the  future  to  include  the  mental  world  in  some  wider 
system  of  relations  in  which  the  mental  and  the  physical 
shall  be  brought  together.     The  objection  is  more  formal 
than  real.     We  come  back,  then,  to  the  original  assertion 
that  we  cannot  make  a  single  observation  that  will  in- 
clude a  mental  event  and  the  physical  event  that  causes 


96  FUNDAMENTALS    OF   PSYCHOLOGY 

it  or  is  caused  by  it,  and  in  consequence  can  obtain  not 
even  an  approximate  picture  of  how  one  is  related  to  the 
other.  There  is  not  even  a  good  analogy  for  the  connec- 
tion, and  most  explanations  are  analogies. 

On  the  other  hand,  the  interactionist  insists  with  great 
firmness  that  mere  failure  to  see  what  happens  when 
two  events  succeed  each  other  uniformly,  does  not  prove 
that  they  do  not  stand  in  some  active  relation,  even  in 
causal  relation  to  each  other.  It  is  very  seldom,  if  ever, 
that  one  can  actually  know  that  some  force  has  passed 
from  one  object  to  another,  or  can  know  anything  of 
what  has  taken  place  between  them.  An  actual  tracing 
of  energy  relations  is  the  exception  rather  than  the  rule. 
In  other  words,  the  relation  between  the  mental  and  the 
physical  series  of  events  is  no  more  unknown  than  is  any 
other  active  relation.  There  is  therefore  no  more  objection 
to  regarding  the  psycho-physical  relation  as  causal  than 
the  relation  between  heating  and  expansion  or  any 
other  simple  physical  relation.  Physical  cause  is  itself 
not  understood,  and,  if  one  goes  deep  enough,  is  as  much 
a  mystery  as  the  relation  of  mind  and  body.  While  one 
may  grant  all  this  very  readily,  it  does  not  necessarily 
follow  that  to  change  from  one  side  to  the  other  too 
often  and  too  quickly  —  to  introduce  mental  elements  into 
the  physical  series  and  physical  into  the  mental  series  — 
may  not  give  rise  to  vagueness  and  uncertainty.  As  a 
matter  of  fact,  while  one  may  admit  that  there  are  causal 
interconnections  between  nervous  system  and  mind, 
it  is  also  true  that  many  arguments  become  vague  if  the 
speaker  jumps  from  one  series  to  the  other  for  an  expla- 
nation.    While  we  shall  admit  that  mind  and  body  un- 


THE    FU^XTIOXS    OF    THE    CEREBRUM  97 

doubtedly  interact,  we  shall  endeavor  as  far  as  possible 
to  keep  the  explanation  of  physical  states  in  terms  of 
antecedent  physical  states,  and  the  explanation  of  mental 
states  in  terms  of  antecedent  mental  states,  and  assume 
as  little  interaction  between  the  series  as  is  possible. 
It  is  necessary  to  accept  an  effect  of  the  sense  organs 
and  sensory  neurones  upon  consciousness  to  understand 
the  material  of  consciousness  and  an  influence  of  volun- 
tary processes  on  muscles  if  we  are  to  understand  action. 
Aside  from  these,  however,  clearness  demands  that  all 
mixing  of  the  two  sets  of  explanations  be  avoided. 

REFERENCES 

BiNG :  Compendium  of  Regional  Diagnosis. 

DuNLAP :  Outline  of  Psychobiolog}'. 

Herrick:  Introduction  to  Neurology^ 

Ladd-Woodworth  :  Physiological  Psychology.     Pp.  13-293, 

Strong  :  Why  the  Mind  has  a  Body. 

;MacDougall:  Bodv  and  Mind. 


CHAPTER  IV 

SENSATION  —  VISION 

We  have  seen  from  our  discussion  of  the  action  of 
the  nervous  system  that  all  nervous  action  starts  in 
sensation  and  leads  to  movement.  The  first  half  of 
this  assertion  is  to  be  our  guiding  principle  in  discussing 
the  qualities  of  consciousness.  All  the  materials  of  our 
consciousness  are  derived  from  sensation.  We  have 
just  as  many  different  sorts  of  consciousness  as  we  have 
qualities  of  sensation,  and  consciousness  persists  ap- 
parently only  so  long  as  impressions  are  playing  upon 
our  sense  organs.  The  old  sensationalists,  Hobbes  and 
Locke,  e.g.,  insisted  that  there  could  be  nothing  in  mind 
that  had  not  previously  been  in  sense.  While  we  do 
not  to-day  accept  the  principle  quite  so  literally  as 
they  did,  yet  it  is  easy  to  see  that  the  fundamental 
qualities  of  mind  are  derived  altogether  from  the  ex- 
ternal senses.  One  can  imagine  no  color  or  sound  that 
has  not  at  some  time  been  seen  or  heard ;  or,  to  put  it 
more  conservatively,  one  can  call  to  mind  no  quality 
of  any  kind  that  has  not  at  one  time  come  through  the 
senses.  One  cannot  picture  the  color  of  an  ultra-violet 
light,  or  think  what  it  would  be  like  if  one  were  suddenly 
to  develop  a  sense  organ  that  might  be  affected  by  it, 
nor  can  one  think  how  the  magnet  might  affect  one  if 

98 


SENSATION  —  VISION  99 

some  sense  organ  should  be  developed  to  respond  to  it. 
Memory,  imagination,  and  reasoning  are  limited  in  the 
qualities  that  they  make  use  of  to  the  bare  materials  of 
sense.  They  may  recombine  them,  they  may  make 
use  of  the  sense  materials  in  new  ways,  but  they  can 
add  no  new  qualities. 

Classification  of  Sensations.  —  The  qualities  of  sen- 
sation might  conceivably  depend  either  upon  the  nature 
of  the  stimulus  or  upon  the  nature  of  the  recei\dng 
organ.  The  popular  mind  accepts  the  former,  but 
most  psychologists  believe  that  they  are  determined 
by  the  character  of  the  sense  organ  or  the  connected 
portions  of  the  nervous  system,  by  the  nature  of 
the  sensory  ends  that  are  turned  outward  to  the 
physical  world.  That  the  nature  of  the  sensation 
does  not  depend  altogether  upon  the  stimulus  is 
evident  from  the  fact  that  different  stimuli  produce 
the  same  sensation  when  they  affect  the  same  sort  of 
nerves.  Thus  we  shall  see  that  heat  waves,  pressure, 
and  heat  or  its  lack  all  produce  the  sensation  of  cold 
when  they  act  upon  a  cold  spot  on  the  skin.  On  the 
other  hand,  the  same  stimulus,  an  electric  current,  e.g., 
produces  a  different  sensation  as  it  acts  upon  different 
kinds  of  sense  organs,  cold  on  a  cold  spot,  light  on  the 
retina,  etc.  These  facts  and  others  seem  to  show  fairly 
conclusively  that  the  nature  of  the  sensation  is  deter- 
mined by  the  receiving  organ,  rather  than  by  the  stimulus 
that  is  applied ;  by  the  character  of  the  receiving  tissue 
that  has  been  developed,  rather  than  by  the  character 
of  the  outside  world.  If  this  be  accepted  provisionally, 
it  furnishes  a  convenient  means  of  classifying  sensations. 


ICX)  FUNDAMENTALS    OF   PSYCHOLOGY 

Could  one  but  determine  the  different  sorts  of  sense 
ends  that  come  to  the  surface  of  the  body  or  are  im- 
bedded in  its  substance,  one  would  also  have  a  complete 
list  of  the  possible  sensations.  In  practice  one  usually 
discriminates  the  sense  quality  first  and  later  discovers 
the  sense  organ,  but  the  classification  nevertheless  is 
assumed  to  be  in  terms  of  the  sense  organ.  We  may 
accept  for  the  moment  the  general  principle  that  the 
number  of  sense  qualities  is  determined  by  the  number 
of  sorts  of  sensory  tissue  that  can  be  stimulated. 

The  classification  of  sensations  still  offers  some  diffi- 
culties, since  the  fundamental  kinds  of  sense  ends  must 
be  grouped  in  some  way  for  convenience  of  treatment. 
In  certain  cases  the  similar  nerves  are  combined  in 
some  one  organ.  Thus  in  the  eye  are  thousands  of 
nerve  ends  stimulated  by  the  same  physical  forces,  and 
giving  rise  to  similar  sensations.  In  the  skin,  on  the 
other  hand,  sense  ends  of  one  kind  are  scattered  indiffer- 
ently over  its  surface,  and  while  popularly  we  speak  of 
the  skin  as  the  sense  organ  of  touch,  there  are  really  at 
least  four  different  kinds  of  sensation  received  from 
the  skin.  Taste  and  smell  offer  an  inconsistency  of  the 
opposite  sort.  The  organs  are  distinct,  but  the  stimuli 
are  closely  similar  and  the  qualities  of  sensation  are  not 
discriminated  by  the  popular  mind,  yet  science  and 
common  sense  follow  the  organ  rather  than  the  quality 
in  making  them  distinct  sense  departments.  One  may 
say,  then,  that  in  classifying  sense  qualities,  the  organ  pro- 
vides the  first  means  of  grouping,  and  within  the  organ 
the  subdivisions  may  be  either  in  terms  of  the  classes 
of  stimuli,  or  of  the  qualities  of  sensation,  or  of  both. 


SEXSATICN  —  \n  SIO>r  Id 

When  one  attempts  to  enumerate  all  possible  sorts  oi 
mental  qualities  or  sensations,  one  sees  very  quickly 
that  there  are  various  kinds  of  differences  that  are  not 
on  exactly  the  same  level.  It  is  not  possible  to  arrange 
all  the  different  kinds  of  sensation  from  any  organ  in  a 
single  series,  members  of  which  shall  differ  from  each 
other  in  one  respect  only.  Thus  in  sound,  we  may 
distinguish  differences  of  pitch  and  also  differences  of 
loudness.  These  vary  independently.  A  high  tone 
may  be  either  loud  or  faint.  These  different  ways  in 
which  sensations  may  vary  are  called  the  attributes  of 
sensation.  How  many  attributes  there  are  is  by  no 
means  a  matter  of  agreement.  All  agree  that  one  must 
distinguish  differences  in  quality  from  differences  in 
intensity.  The  quality  may  be  said  roughly  to  depend 
upon  the  specific  character  of  the  sense  organ  stimulated, 
while  the  intensity  depends  upon  the  degree  to  which 
the  organ  is  stimulated.  There  are  probably  exceptions 
to  both  of  these  statements.  In  light,  for  example, 
the  strength  of  .stimulus  probably  in  part  determines 
the  organ  stimulated.  Faint  lights  are  probably  seen 
by  one  set  of  organs,  bright  lights  by  another.  In  the 
eye,  too,  even  with  bright  lights,  variation  in  physical 
intensity  is  not  distinguished  from  change  in  quahty 
of  excitation.  The  grays  correspond  to  changes  in 
strength  of  light  but  the  untrained  observer  puts  them 
on  the  same  level  with  change  in  color.  Black,  white, 
and  gray  are  popularly  regarded  as  colors.  But  in  all 
other  senses,  the  distinction  in  quality  and  intensity 
offers  little  difficulty,  and  these  two  attributes  are 
recognized  by  practically  all  psychologists. 


102  FUNDAMENTALS   OF  PSYCHOLOGY 

Attributes  of  Sensation.  —  More  difficult  it  is,  however, 
to  dispose  of  some  of  the  other  attributes  sometimes 
ascribed  to  sensations.  -Thus  every  sensation,  or  more 
truly  every  object,  possesses  extent,  and  every  event 
occupies  time,  has  duration.  Many  authorities  speak 
of  extent  and  duration  as  attributes  of  sensation,  as 
fundamental  ways  in  which  sensations  may  vary.  In 
the  simplest  cases,  these  ways  of  varying  seem  im- 
mediate and  unanalyzable,  but  in  many  more  instances 
it  is  possible  to  show  that  the  appreciation  both  of  ex- 
tent and  of  duration  depends  upon  more  complicated 
mental  operations.  They  belong  rather  to  the  object 
than  to  the  sensation  as  such.  In  consequence  it  is 
more  convenient  to  treat  them  both  under  the  head 
of  perception,  as  a  process  of  mental  elaboration  of 
sensations,  rather  than  as  an  immediate  characteristic 
of  the  elementary  sensation.  Very  much  the  same 
statement  may  be  made  of  clearness  and  feeling  tone, 
regarded  by  some  authorities  as  attributes.  It  is  at 
least  a  question  whether  feeling  is  not  independent  of 
sensation  and  equally  primary  as  a  mental  state.  Clear- 
ness is  a  change  induced  in  sensations  as  a  result  of  their 
connections  in  consciousness,  not  an  attribute  of  sensa- 
tions themselves.  Whether  we  are  to  regard  them  as 
irreducible  parts  of  sensations,  or  as  independent  ele- 
ments, or  as  accidents  of  the  ways  of  receiving  the 
sensation,  can  be  best  discussed  in  a  later  chapter. 
For  the  present  we  may  content  ourselves  with  the 
statement  that  sensations  vary  in  specific  quality  which 
depends  primarily  upon  the  nature  of  the  receiving 
end  organ,  secondarily  upon  the  character  of  the  stimu- 


SENSATION  —  VISION  103 

lus;  and  in  intensity,  which,  in  its  turn,  is  dependent 
upon  the  amount  of  stimulation  that  affects  the  sense 
organ.  Considering  qualities  alone,  the  sensations  fall 
into  certain  series,  marked  by  continuous  change  in 
some  one  respect.  It  is  impossible,  however,  to  find 
similar  continuous  changes  from  series  to  series.  Thus 
colors  show  a  continuous  series  of  -tone ;  sounds  show 
a  continuous  series  of  pitches  ;  but  thfere  is  no  gradation 
from  sound  to  sight.  Through  each  quality  runs  a 
series  of  intensities  which  is  regularly  graduated  from 
zero  to  a  maximum.  We  shall  discuss  first  the  qualities 
in  their  dependence  upon  the  organ  and  the  stimulus, 
then  the  intensities. 

The  Stimuli  for  Vision.  —  We  may  begin  with  the 
most  important,  if  one  of  the  most  complicated  senses, 
vision.  The  physical  stimuli  for  sight  are  vibrations 
in  the  etheir  ranging  from  400  Xo  800  fJLfM  ^  in  length. 
Helmholtz  under  favorable  circumstances  saw  rays  >^is^ 
long  as  835  \  and  as  short  as  318  X.  There  was  probably 
some  error  from  fluorescence  at  the  short  wave  end, 
since  the  retina  has  a  certain  amount  of  fluorescence  of 
its  own.  Between  these  limits  lies  the  visible  spectrum 
from  red  to  violet.  We  give  names  to  dift'erent  quali- 
ties, but  it  is  somewhat  difficult  to  say  just  where  one 
color  changes  into  another,  since  the  names  given  are 
not  matters  of  agreement.  The  physical  relations  have 
little  significance  for  the  sensation  quality.  They  afford 
little  suggestion  of  the  nature  or  condition  of  color 
qualities  and  very  few  of  the  laws  of  color  can  be  stated 

^  MM  means  thousandths  of  a  thousandth  of  a  miUimetre.     This  is 
usually  expressed  as  X. 


I04  FUNDAMENTALS    OF   PSYCHOLOGY 

in  terms  of  the  wave  lengths  of  light.  We  must  turn 
from  the  physical  to  the  physiological  for  an  explana- 
tion of  the  phenomena  that  interest  us.  For  this  we 
must  consider  the  essential  features  of  the  structure  of 
the  eye. 

The  Eye  and  its  Appendages.  —  The  eye  is  a  part  of 
the  brain  that  has  come  to  the  surface  of  the  body  in 
the  course  of  its  development,  has  increased  the  primary 
sensitiveness  of  nerve  tissue  to  light  by  the  develop- 
ment of  new  photochemical  substances,  and  has  gained 
a  system  of  lenses  and  grown  protective  coats,  and  ac- 
quired a  mounting  that  permits  of  ready  turning  in 
all  directions.  The  eyes  are  mounted  in  deep  conical 
sockets  in  the  skull,  where  they  are  well  protected.  The 
eyeball  is  kept  in  its  place  in  the  socket  by  loose  fibres 
of  connective  tissue,  by  a  padding  of  fat,  and  by  the 
muscles  that  turn  it.  To  prevent  foreign  particles 
from  entering  the  socket,  the  front  is  closed  by  the  con- 
junctiva, a  membrane  continuous  with  the  inner  lining 
of  the  eyelids  and  the  outer  surface  of  the  eyeball. 
Three  pairs  of  muscles  turn  it.  The  discussion  of  their 
action  may  well  be  left  over  to  the  chapter  on  space 
perception,  for  it  is  in  that  connection  that  their  action 
is  important.  The  padding  of  fat,  the  conjunctiva, 
and  the  loose  connective  tissue  at  once  hold  the  centre 
of  the  eye  fairly  well  fixed,  and  at  the  same  time  permit 
it  to  turn  easily  about  its  centre. 

The  Structure  of  the  Eye.  —  The  eyeball  is  approxi- 
mately a  sphere  a  little  less  than  an  inch  in  diameter 
(23-24  mm.).  The  spherical  shape  is  given  it  by  the 
outer  or  sclerotic  coat,  which  is  kept  distended  by  the 


SENSATION  —  VISION  105 

intraocular  pressure  due  to  its  connection  with  the 
general  circulation.  This  pressure  amounts  to  about 
25  mm.  of  mercury  in  the  normal  individual.  The  eye- 
ball has  three  principal  coats.  The  sclerotic  is  a  tough 
protective  coat  of  connective  tissue.  Inside  the  scle- 
rotic is  the  choroid  coat,  made  up  mostly  of  blood  vessels 
with  some  muscles  and  nerve  fibres.  Still  farther  within 
is  the  retina,  the  nervous  structure  and  true  sense  organ. 
Between  the  choroid  and  the  retina  is  a  layer  of  large 
pigment  cells  regarded  by  some  authorities  as  belonging 
to  the  choroid,  by  others  as  an  independent  intermediate 
coat,  and  by  still  others  as  a  part  of  the  retina.  The 
difference  of  opinion  is  probably  due  to  the  fact  that 
the  cells  are  in  a  different  position  in  the  light-adapted 
and  the  dark-adapted  eye.  When  the  eye  has  been 
for  a  long  time  in  the  light,  the  cells  are  well  down  in 
the  outer  coat  of  the  retina,  and  adhere  to  it.  In  the 
dark-adapted  eye,  on  the  other  hand,  they  are  well 
outside  and  come  away  from  it  freely  when  the  choroid 
is  stripped  off.  They  are  relatively  large  hexagonal  cells, 
and  like  the.  black  paint  on  the  inside  of  a  camera 
insure  the  absorption  of  errant  light  rays. 

Each  of  these  coats  shows  modifications  in  some  part. 
The  sclerotic  coat  in  the  front  of  the  eye  has  a  shorter 
radius  of  curvature,  is  transparent,  and  bulges  forward 
as  a  part  of  the  lens  system.  Here  it  is  called  the  cornea. 
It  can  be  seen  to  protrude  from  the  sclerotic  if  one  will 
look  across  the  eye  of  another.  Back  of  the  cornea  is 
a  chamber  filled  with  a  watery  fluid.  This  is  the  an- 
terior chamber,  and  the  fluid,  the  aqueous  humor.  In 
this  chamber  is  an  extension  of  the  choroid  coat,  the 


io6 


FUNDAMENTALS  OF  PSYCHOLOGY 


iris,  which  is  not  attached  to  the  sclerotic  or  cornea, 
but  extends  across  the  anterior  chamber  in  the  aqueous 


Bet. 
Chon 


Scler, 


Fig.  37.  —  Section  of  the  eye;  Scler.,  sclerotic  coat;  Chor.,  choroid;  Ret., 
retina;  Opt.,  optic  nerve;  Fov.  c,  foves;  Pr.  cil.,  the  ciliary  muscle  or  ciliary 
process;  cow;.,  conjunctiva ;  Cow.  c»^,  the  anterior  chamber ;  corpus  intrcum, 
the  vitreous  humor  that  fills  the  posterior  chamber.  (From  Angell's  "Psy- 
chology.") 

humor.     In  its  centre  is  a  hole,   the  pupil.     The  iris 
gives  the  color  that  is  regarded  popularly  as  characteristic 


Sensation  —  vision  107 

of  the  eye.  In  the  dark  types,  it  is  much  pigmented  and 
passes  for  black  or  brown ;  blue  and  gray  eyes  are  less 
pigmented.  The  size  of  the  pupil  is  determined  by  the 
relative  degree  of  contraction  of  two  muscles  or  sets  of 
muscles:  (i)  a  muscle  with  radial  fibres,  the  dilator  of 
the  pupil,  and  (2)  the  sphincter,  a  muscle  with  circular 
fibres.  These  are  controlled  reflexly  by  the  degree  of 
stimulation  of  the  optic  nerve.  The  contraction  in 
constriction  is  caused  by  a  reflex  (p.  60).  Dilation 
involves  a  reflex  through  a  long  path  down  to  the  cord 
and  back  through  the  cervical  sympathetic  nerve  and 
superior  sympathetic  ganglion  to  the  eye.  The  wide- 
spread course  of  the  pupillary  reflex  makes  it  very 
important  in  the  diagnosis  of  nervous  diseases  in  general. 
It  is  affected  by  lesions  in  many  different  structures. 
In  the  normal  individual,  the  constriction  takes  place 
promptly  on  increase  of  illumination,  while  dilation  is 
relatively  slow  because  of  the  long  course  through  the 
sympathetic  nerves.  The  function  is  in  part  protective 
by  reducing  strong  lights,  but  also  has  somewhat  the 
eft'ect  of  the  diaphragm  of  a  camera.  It  gives  better 
definition  because  it  stops  down  the  pupil  when  the 
light  is  strong  enough  to  permit  and  when  the  light  is 
faint  it  admits  more.  Constriction  of  the  pupil  also 
accompanies  accommodation  to  near  objects. 

The  Mechanism  of  Accommodation.  —  Back  of  the 
iris  and  directly  against  it  is  the  lens,  the  most  important 
of  the  optical  mechanisms.  It  consists  of  a  large  number 
of  layers.  The  front  surface  of  the  lens  has  in  youth 
a  natural  radius  of  curvature  of  4.8  mm.,  the  posterior 
of  4.6  mm.     Ordinarily,  however,  it  is  held  flattened 


io8 


FUNDAMENTALS   OF   PSYCHOLOGY 


by  the  strain  of  the  suspensory  ligament.  This  ex- 
tends from  the  ciliary  processes  on  the  ciliary  muscle 
to  the  edge  and  the  front  and  back  surfaces  of  the  lens. 
The  lens  with  its  attachments  constitutes  the  mechanism 
of  accommodation  —  makes  possible  focussing  upon 
objects  at  different  distances.  The  active  agent  is  the 
ciliary  muscle.  It  is  attached  to  the  sclerotic  coat 
near  the  angle  formed  by  the  increasing  curvature  of 


FAR 


NEAPv 


Fig.  38.  —  Change  in  lens  and  ciliary  muscle  in  accommodation.  Left  shows  ac- 
commodation for  distant,  right  for  near  objects.     (From  Foster's  Physiology.  ) 

the  cornea,  and  the  fibres  run  back  to  lose  themselves 
in  the  structure  of  the  choroid  coat.  The  suspensory 
ligament  is  attached  to  the  side  of  the  muscle  instead 
of  the  end  as  are  the  tendons  of  other  muscles,  so  that 
the  contraction  of  the  muscle  means  relaxation  of  tension 
on  the  suspensory  ligament  rather  than  increase  of  ten- 
sion. When  the  tension  of  the  suspensory  ligament 
is  released,  the  lens  resumes  its  normal  shape  owing  to 
its  elasticity.  As  one  grows  older,  the  lens  becomes 
less  and  less  elastic,  and  accommodation  practically  dis- 


SENSATION  —  VISION  1 09 

appears  between  45  and  55  years.  Back  of  the  lens 
is  the  large  posterior  chamber  of  the  eye,  filled  with  the 
vitreous  humor,  so  called  because  it  has  the  consist- 
ency of  molten  glass.  This  fills  the  cavity  between 
the  retina  and  the  lens. 

Dioptrics  of  the  Eye.  —  Regarded  as  an  optical  sys- 
tem, the  function  of  the  eye  is  to  project  an  image  of  an 
object  upon  the  retina.  The  important  refracting  sur- 
faces are  three,  the  front  surface  of  the  cornea  and  the 
front  and  back  surfaces  of  the  lens.  The  indices  of 
refraction  of  the  cornea,  and  of  the  aqueous  and  vitreous 
humors,  are  approximately  identical,  and  each  is  ap- 
proximately the  same  as  that  of  water,  —  1.337.  The 
refractive  index  of  the  lens  in  practical  effect  is  1.437. 
Calculation  of  the  optical  efficiency  of  the  system  of 
lenses  in  the  eye  from  these  figures,  assuming  an 
average  radius  of  curvature  of  the  cornea  of  8  mm.,  of 
the  front  surface  of  the  lens  of  10  mm.,  and  of  the  back 
surface  of  6  mm.,  gives  it  a  value  of  from  60  to  66  diop- 
ters.^ An  eye  with  a  length  of  axis  of  22  mm.  must 
have  a  strength  of  66  diopters  if  the  rays  are  to  be 
focussed  upon  the  retina.  It  is  assumed  that  the  normal 
eye  has  a  strength  of  64.50  D  and  that  the  nodal  point, 
the  point  through  which  all  light  rays  may  be  assumed 
to  pass,  is  15.5  mm.  from  the  retina  and  about  7.3  back 
of  the  cornea.  For  most  calculations  one  may  use  the 
reduced  eye  of  Listing,  a  simpler  structure  with  a  re- 

^  A  diopter  is  defined  as  the  strength  of  a  lens  that  will  bring  parallel 
rays  to  a  focus  at  a  distance  of  one  metre.  The  number  of  diopters  of  a 
lens  is  determined  by  dividing  one  metre  by  the  length  of  its  principal 
focus.  A  lens  that  brings  parallel  rays  to  a  focus  at  20  mm.  has  a  strength 
of  50  diopters. 


no 


FUNDAMENTALS   OF   PSYCHOLOGY 


fractive  system  that  has  the  same  optical  function  as 
the  eye.  This  has  a  single  surface  2.1  mm.  back  of  the 
surface  of  the  cornea,  with  a  radius  of  curvature  of  5.2 
mm.  and  a  refractive  index  of  1.33.  The  size  of  the 
retinal  image  cast  by  objects  in  the  outside  world  and 
other  relations  of  light  rays  are  sufficiently  accurately 
determined  for  most  purposes  if  one  assumes  that  the 
nodal  point  is  15.5  mm.  in  front  of  the  retina,  and  that 
principal  rays  pass  through  it  on  the  way  to  the  retina. 


Fig.  39.  —  The  formation  of  the  retinal  image.  Shows  refraction  of  three 
rays  of  Ught  from  X  and  Y  that  focusses  them  on  the  retina,  and  the  inversion 
of  the  object.  P  is  refracting  surface  of  reduced  eye.  (From  Foster's 
"Physiology.") 

The  Structure  of  the  Retina.  —  The  retina  is  prac- 
tically a  part  of  the  central  nervous  system.  It  is  a 
very  thin  coat  of  nerve  tissue  from  .3  to  .35  mm.  in 
thickness.  If  we  accept  the  neurone  theory,  the  retina 
is  composed  of  three  layers  of  neurones,  one  with  the 
modified  sensory  epithelium,  the  rods  and  cones,  which 
receive  the  stimulation ;  one  intermediate  layer,  the 
bipolar  cells ;  and  one  whose  cell  bodies  are  the  large 
ganglion  ©ells  nearest  the  vitreous  humor.  In  the  older 
histologies  it  is  said  that  there  are  ten  coats,  but  these 
are   composed  of   the  various  masses  of  cell   bodies^ 


SENSATION  —  VISION  III 

axones,  dendrites,  and  synapses  between  the  neurones, 
and  need  not  concern  us  now  that  we  can  see  their  rela- 
tions to  the  neurones.  The  rods  and  cones  are  farthest 
away  from  the  light  directly  in  front  of  the  layer  of 
pigment  cells  and  the  choroid  coat.  The  cones  are 
relatively  short  and  thick,  from  4-6  /-t  (yu,  =  .001  mm.) 
in  diameter  and  30-40  /^  long.  The  rods  are  longer  and 
more  slender,  2-4  /i  across,  and  40-60  ti  long.  They 
are  crow^ded  about  as  closely  together  as  is  possible,  so 
that  the  distance  from  centre  to  centre  of  the  elements 
is  not  much  greater  than  the  diameter  of  the  single 
element.  In  both  the  rods  and  the  cones  can  be  dis- 
tinguished an  outer  section  and  an  inner  section.  Just 
at  the  base  of  the  cones  and  a  little  distance  away  from 
the  rods  is  a  swelling  that  probably  constitutes  the  cell 
of  the  neurone.  The  axones  of  the  rods  and  cones 
come  into  contact  with  the  dendrites  of  the  bipolar 
cells,  and  the  axones  of  these  in  turn  with  the  dendrites 
of  the  large  ganglion  cells.  In  the  fovea  it  is  said  that 
a  cone  connects  with  a  single  bipolar  cell  and  that  in 
turn  with  only  one  ganglion  cell.  Thus  the  impulse 
from  each  cone  in  the  fovea  is  kept  separate  all  the  way 
to  the  brain.  In  other  portions  single  bipolar  cells 
make  connections  with  more  than  one  rod  or  cone.  In 
addition  to  these  direct  lines  of  connection  with  the 
central  nervous  system,  there  is  a  layer  of  cells  between 
the  rods  and  cones  and  the  bipolar  cells  which  serves 
to  connect  different  rods  and  cones  horizontally.  It  is 
possible,  even  probable,  that  some  of  the  spreading  of 
impulses  in  contrast  and  irradiation  takes  place  over 
.these  horizontal  cells.     In  addition  to  these  nerve  cells 


112 


FUNDAMENTALS   OF  PSYCHOLOGY 


Fig.  40.  —  Section  of   the  retina,  showing   the   neurones.     (After  Cajal,  from 
Howell's  "  Physiology.") 


there  art  everywhere  in  the  retina  supporting  cells  of 
non-nervous  tissue,  the  so-called  Miiller  cells.  In  the 
innermost  layer  are  fibres,  the  axones  of  the  ganglion 


SENSATION  —  VISION 


113 


cells,  which  unite  to  constitute  the  optic  nerve  and  carry 
impulses  to  the  cerebral  nervous  system. 

Fovea  and  Blind  Spot.  —  Certain  parts  of  the  retina 
show  modifications  from  this  general  arrangement  that 
make  them  of  particular  interest.  One  of  these,  the 
fovea,  lies  near  the  centre  of  the  retina.  It  is  the  point 
of  clearest  vision,  the  point  turned  toward  objects  we 
desire  to  see  distinctly.  As  its  name  implies,  it  is  a  pit 
or  depression  in  the  retina  made  by  a  drawing  apart  of 


Fig.  41.  —  Section  of  the  fovea.  It  may  be  seen  that  the  axones  of  the  cones 
extend  toward  the  periphery  to  make  connection  with  bipolar  and  ganglion  cells. 
On  the  left  may  be  seen  the  central  cells  to  which  the  visual  impulse  is  carried. 
(From  Cajal.) 

the  front  coats  of  the  retina.  This  pit  is  due  to  the  fact 
that  axones  which  lead  off  from  the  cones  go  towards 
the  periphery  of  the  fovea,  and  the  bipolar  and  ganglion 
cells  with  their  axones  and  the  blood  vessels  which  supply 
the  region  are  to  one  side  of  the  cones  rather  than  in 
front  of  them,  — between  them  and  the  h'^ht  ps  in  other 
portions  of  the  retina.     The  cones  are  he  rest  the 

surface,  and  light  need  not  pass  through  so  muci.  "etinal 
tissue.  In  the  fovea,  too,  are  found  only  cones,  and  these 
are  as  long  and  slender  as  rods,  so  that  the  centres  are 


114  FUNDAMENTALS    OF   PSYCHOLOGY 

only  about  2-4  ft  apart.  In  the  neighborhood  of  the 
fovea  the  retina  has  a  yellowish  tinge.  The  fovea  is 
0.3-0.4  mm.  wide  at  the  bottom  and  0.5-0.75  at  the 
top.  The  yellow  spot  is  much  larger,  some  six  milK- 
metres  in  diameter.  In  the  literature  the  fovea,  point 
of  clearest  vision,  and  yellow  spot  are  used  almost  inter- 
changeably. This  is  only  approximately  accurate,  as 
the  dimensions  of  the  yellow  spot  and  fovea  show. 
As  one  proceeds  from  the  fovea,  the  rods  become  rela- 
tively more  numerous,  the  cones  less  numerous,  until 
at  the  periphery  the  cones  are  almost  entirely  lacking. 
A  third  local  difference  that  offers  something  of  interest 
is  the  area  at  which  the  optic  nerve  leaves  the  eye. 
This  contains  no  rods  or  cones,  but  only  the  fibres, 
axones  of  the  large  ganglion  cells,  which  unite  to  form 
the  optic  nerve.  It  is  an  area  about  1.5  mm.  (4°-6°) 
in  diameter,  about  5  mm.  (15°)  to  the  nasal  side  of  the 
fovea. 

The  Rods  and  Cones  are  the  Organs  of  Vision.  — 
There  is  very  good  evidence  that  the  rods  and  cones 
are  the  organs  of  vision,  i.  Vision  is  absent  where  the 
rods  and  cones  are  lacking  at  the  entrance  of  the  optic 
nerve.  2.  The  shadows  of  the  blood  vessels  in  the 
outer  coat  of  the  retina  may  be  seen  under  suitable 
conditions,  and  H.  Muller  has  measured  the  distance 
of  these  blood  vessels  from  the  perceiving  organs  by  a 
method  of  triangulation  based  on  the  apparent  dis- 
placement of  their  shadows  with  known  motion  of  the 
light  outside.  He  found  that  the  blood  vessels  were 
from  0.17-0.33  mm.  from  the  perceiving  coat,  and 
measurements   of    the    actual    distance   in    the   retina 


SENSATION  —  VISION 


115 


between  blood  vessels  and  the  layer  of  rods  and  cones 
was  from  0.2  and  0.3  mm. 

The  problem  as  to  what  changes  go  on  in  the  retina 
when  it  is  stimulated,  what  actually  makes  one  see, 
has  aroused  much  discussion.  Two  changes  can  be 
seen  to  take  place.  One  is  a  change  in  the  color  of  the 
pigment  in  the  rods.  The  retina  of  a  frog  killed  in  the 
light  has  a  very  light  color.  If,  however,  it  be  killed 
after  being  kept  a  long  time  in  the  dark,  the  rods  have 
a  delicate  pur- 
ple hue.  Pic- 
tures may  be 
taken  with  the 
retina  of  a  rab- 
bit. If  the  rab- 
bit looks  for  a 
little  time  at 
the  window  of 
a  dark  room  in 
which  it  is 
placed,  then  is  killed  and  the  retina  fixed  as  one  would  fix  a 
photographic  plate,  a  picture  of  the  window  can  be  seen 
on  the  retina.  Such  an  optogram  is  shown  in  Figure  47. 
It  has  also  been  demonstrated  by  a  similar  method 
that  the  rods  contract  in  a  bright  light,  and  that  the 
pigment  cells  in  the  layer  just  outside  of  the  retina  move 
in  between  the  outer  joints  of  the  rods.  Of  these  changes 
only  the  bleaching  of  the  visual  purple  has  been  given 
any  meaning,  and  that,  as  we  shall  see,  acts  only  as  a 
sensitizer  of  the  retina.  The  positions  may  be  compared 
in  Figure  48. 


Fig.  42.  —  Optogram,  i  shows  the  normal  appear- 
ance of  the  rabbit's  retina  ;  2  shows  the  condition  when 
the  rabbit  has  been  permitted  to  look  at  the  window  of 
the  dark  room  and  then  is  killed  while  still  in  the  dark 
and  the  retina  fixed  as  a  photographic  negative  is  fixed. 


ii6 


FUNDAMENTALS   OF  PSYCHOLOGY 


The  Qualities  of  Vision.  —  All  theories  of  vision  have 
been  based  upon  a  study  of  visual  phenomena  rather 
than  on  a  study  of  the  physiological  processes.  Explana- 
tions of  physiological  processes  develop  from  the  facts  of 
sight  rather  than  the  other  way  round.  The  sensations 
from  the  eye  may  be  divided  into  four  different  series. 
The  first  corresponds  to  the  pure  spectral  colors  at 
maximum  saturation,  the  series 
ranging  from  red  to  violet  together 
with  the  purples.  These  vary  with 
the  wave  length.  The  second,  the 
brightness  or  achromatic  series,  cor- 
responds to  the  different  intensities 
of  all  wave  lengths  as  in  sunlight  or, 
strictly,  of  suitably  mixed  wave 
Fig.  43.- Showing  posi-   jgngths,  and   the  sensation  series 

tion  of  pigment  cells,     in  the  ^        ' 

dark  adapted  eye   (right)    varies  from  black  to  whitc  through 

they  are  outside  of  the  outer     ,,  rr-n        .i  •    j  •        •     .i 

layer  of  the  rods  and  cones;  the  grays.  The  third  scrics  IS  the 
in  bright  adapted  eye  (left)    efje^t  of  change  in  the  intensity  of 

they  are  well  down  between  ^  " 

the  rods  and  cones.  (From  a  single  wavc  length  and  ranges 
SivenandWendt.)  ^^^^  ^^^  ^^^^  Saturated  or  mmr 

plete  color  to  black  at  a  slight  intensity  of  stimulus, 
and  again  from  the  most  saturated  color  to  a  whitish 
hue,  at  the  maximum  intensfty.  The  fourth  series 
corresponds  to  the  mixture  of  a  single  wave  length  with 
grays  of  the  same  intensity.  The  sensations  that  result 
range  from  the  pure  color  to  a  gray.  The  amount  of 
the  admixture  determines  what  is  called  the  degree  of 
saturation  of  the  color.  The  pure  color  is  saturated, 
and  the  greater  the  amount  of  gray,  the  less  the  satura- 
tion.    The  last   two  variations  are  frequently  mixed  : 


SENSATION  —  VISION 


117 


saturation  and  brightness  frequently  change  together. 
The  entire  series  of  color  qualities  may  be  represented 
on  a  double  pyramid  (Fig.  44).  The  color  tones  lie 
along  the  sides  of  the  square.  Black  stands  at  the 
bottom,  white  at  the  apex,  and  the  series  of  grays 
lies  along  the  connecting  line 
through  the  centre.  On  the 
outside  of  the  figure  the  shades 
of  the  various  colors  corre- 
sponding to  reduced  intensity 
of  the  pure  lights  are  repre- 
sented from  the  central  square 
downward,  the  tints  corre- 
sponding to  increased  intensity, 
from  that  base  upward.  The 
various  degrees  of  saturation 
are  represented  by  distances 
on  the  base  of  the  pyramid 
from  the  outer  square,  where 
lie  the  spectral  colors,  to  the 
centre  that  represents  the 
neutral  gray.  The  color  tones 
are  more  and  more  mixed  with 
the  neutral  tint  from  the  cir- 
cumference inward  until  color  altogether  disappears 
in  the  centre.  The  fact  that  the  color  may  be  mixed 
with  ^  gray  of  greater  or  less  brightness  and  so  re- 
duced in  saturation  and  changed  in  brightness  at 
the  same  time,  can  be  represented  on  the  pyramid  by 
lines  from  the  base  of  our  double  pyramid  to  a  point 
on  the  central  line  at  any  distance  above  or  below  the 


Fig.  44.  —  Color  Pyramid. 
(From  Titchener's  "  Textbook  of 
Psycholog>'.") 


Il8  FUNDAMENTALS    OF   PSYCHOLOGY 

base.  That  the  spectral  colors  are  of  different  bright- 
nesses has  been  represented  by  tilting  the  square  base 
more  or  less,  making  the  green  and  yellow  end  higher 
than  the  red  and  blue.  We  shall  treat  each  of  these 
series  of  sensations  separately  as  far  as  possible. 

We  may  begin  with  the  colors  of  the  spectrum.  The 
spectrum  is  a  continuous  series  of  colors  which  shade 
one  into  the  other  with  no  breaks  readily  observed  at 
the  first  glance.  The  one  fact  that  has  been  emphasized 
by  direct  observation  is  that  there  are  certain  turning 
points  in  the  apparently  continuous  series,  points  where 
one  quality  gradually  disappears  and  another  gradually 
begins  to  show  itself.  Thus,  at  the  long-wave  end,  red 
predominates.  As  one  moves  the  eye  toward  the  short- 
wave end,  red  gradually  becomes  less  and  less  pronounced 
until  it  is  finally  lost  at  588  X  in  the  yellow,  which  has 
also  been  present  in  some  degree  from  the  beginning. 
When  red  disappears,  green  begins  to  appear  and  gradu- 
ally increases.  In  the  meantime  yellow  gradually 
diminishes  in  amount  until  it  disappears  at  526  X  and 
blue  takes  its  place.  Still  another  of  these  critical 
points  occurs  farther  on  at  484  X,  where  the  green  dis- 
appears and  is  replaced  by  red  in  the  violet  colors  at 
the  short-wave  end. 

Color  Mixture.  —  The  terms  we  have  used  imply  that 
there  are  in  the  spectrum  relatively  few  simple  colors 
and  that  any  two  of  these  may  be  distinguished  in  the 
intermediate  colors.  All  theories,  ancient  and  modern, 
have  been  an  attempt  to  discover  just  what  these  simple 
colors  are  and  to  determine  how  they  combine  to  pro- 
duce the  other  colors.     Needless  to  say  there  has  not 


SENSATION  —  VISION  1 19 

been  agreement  as  to  how  many  or  what  these  elemen- 
tary processes  are,  but  these  dilierences  may  best  be 
discussed  after  the  facts  have  been  presented.  The 
first  experimental  indication  of  the  fact  that  most  colors 
are  compound  is  obtained  from  color  mixing.  Colors 
may  be  mixed,  either  by  ha\dng  two  different  wave 
lengths  of  light  fall  upon  the  same  spot  of  the  retina 
at  the  same  time,  or,  more  conveniently,  by  rotating 
disks  of  the  colors  to  be  mixed  so  rapidly  that  one  color 
appears  before  the  effect  of  the  other  has  disappeared. 
Both  methods  give  approximately  the  same  results. 
The  first  law  of  color  mixture  is  that  tw^o  spectral  colors 
when  irdxed  give  a  color  that  lies  between  them  in  the 
spectrum.  When  the  colors  lie  near  together,  the  re- 
sulting color  approaches  saturation;  as  the  two  com- 
ponents come  from  points  farther  apart,  the  saturation 
becomes  less.  Not  only  may  we  obtain  spectral  colors 
from  the  mixture  of  spectral  colors,  but ^il  different  pro- 
portions of  the  extreme  ends  of  the  spectrum  be  mixed, 
colors  are  produced  that  correspond  to  no  single  wave 
length  but  are  nevertheless  true  color  tones  of  a  high 
degree  of  saturation.  These  are  the  purples,  mauves, 
and  other  similar  qualities.  Since  they  grade  from  red 
to  violet,  they  may  be  regarded  as  filling  the  gap  be- 
tween the  two  ends  of  the  spectrum.  For  sensation, 
then,  the  series  of  colors  can  best  be  pictured  as  a  closed 
figure  rather  than  as  a  straight  line.  The  direct  psycho- 
logical evidence  for  this  is  that  the  two  ends  of  the 
spectrum  are  more  alike  than  are  points  nearer  together. 
Violet  has  a  greater  similarity  to  red  than  has  any 
spectral  color  beyond  pure  yellow,  and  the  two  ends 


120  FUNDAMENTALS   OF  PSYCHOLOGY 

of  the  spectrum  may  be  joined  by  suitable  mitxures  of 
the  extreme  colors.  For  this  reason,  among  others, 
the  colors  have  been  schematically  arranged  either  on 
a  circle,  on  a  triangle,  or  on  a  square.  The  circle  rep- 
resents merely  the  fact  that  the  ends  of  the  spectrum 
tend  to  come  together ;  the  other  two  indicate  the 
number  of  primary  colors  that  are  assumed  to  combine 
to  produce  the  whole  series.  Those  who  assume  that 
there  are  three  simple  colors  prefer  to  represent  the 
series  by  a  triangle  with  red  at  one  angle,  green  at  one, 
and  blue  at  the  other.  The  upholders  of  the  four-color 
theory,  on  the  contrary,  choose  a  square,  with  red,  green, 
yellow,  and  blue  at  the  corners. 

Primary  Colors.  —  That  the  spectral  colors  are  derived 
from  a  relatively  small  number  of  simple  colors  seems 
demonstrated,  first,  by  the  fact  that  colors  similar  to 
those  produced  on  the  retina  by  single  wave  lengths 
of  light  can  also  be  excited  by  stimulating  the  retina 
with  two  different  wave  lengths  suitably  chosen;  and 
secondly  by  the  fact  that  the  purples,  which  physically 
are  always  mixed  colors,  seem  just  as  true  colors  as 
those  produced  by  a  single  wave  length.  Irrespective 
of  the  number  and  character  of  the  simple  colors,  it  is 
assumed  by  all  theories  that  there  are  separate  sub- 
stances or  sense  ends  in  the  retina  for  each  of  the  primary 
colors,  and  that  these  simple  structures  or  processes 
combine  their  effects  in  some  way  in  the  production  of 
composite  colors.  It  is  further  asserted  that  other  than 
the  primary  colors  aroused  by  single  wave  lengths  are 
really  mixed  colors,  physiologically.  Thus  blue-green 
in  the  spectrum  produced  by  a  single  wave  length  is ; 


SENSATION  —  VISION  121 

physiologically  compound,  due  to  the  simultaneous 
action  of  the  blue  and  the  green  organ  or  process.  Just 
how  many  primary  colors  there  are  and  what  they  are 
are  still  matters  of  some  dispute  upon  which  these 
facts  of  color  mixture  throw  no  light.  Helmholtz 
assumed  that  there  were  three  primary  colors,  red, 
green,  and  blue  or  violet.  Helmholtz  based  his  selec- 
tion upon  the  fact  that  all  the  other  spectral  colors 
may  be  obtained  from  these  three  in  a  high  degree  of 
saturation.  Hering,  on  the  contrary,  asserted  that 
there  must  be  four  primary  colors,  red,  yellow,  green, 
and  blue.  The  evidence  for  the  selection  of  four  may 
best  be  given  in  connection  with  phenomena  to  be  dis- 
cussed later. 

The  Nature  of  White  Light.  —  A  second  law  of  color 
mixing  is  that  certain  spectral  colors  when  mixed  in 
the  right  proportions  produce,  not  an  intermediate 
color,  but  a  colorless  sensation,  a  gray,  whose  shade 
depends  upon  the  amplitude  of  the  light  waves.  Colors 
which  cancel  each  other  in  this  way  are  called  comple- 
mentary colors.  For  the  four-color  theories,  this  fact 
serves  further  to  define  the  primary  colors,  since  Hering 
assumes  that  the  primary  colors  are  also  complemientary. 
Red  is  the  complement  of  green,  and  blue_of  yellow.  For 
the  three-color  theory  no  evidence  is  gained  in  support 
of  the  primacy  of  the  colors  it  assumes,  but  it  does 
make  it  necessary  to  select  certain  colors  that,  taken 
together,  shall  make  white  or  gray,  shall  be  colorless. 
This  brings  us  to  a  consideration  of  the  physical  nature 
of  white  light  ^\^th  its  darker  tones  of  gray  and  black. 
There  are  no  single  wave  lengths  that  give  rise  to  these 


122  FUNDAMENTALS    OF   PSYCHOLOGY 

brightnesses.  They  are  always  compounded  out  of  a 
number  of  wave  lengths.  In  the  sunlight  all  the  colors 
of  the  spectrum  are  present,  but  the  result  for  sensation 
is  a  somewhat  yellowish  white,  owing  to  dominance  of 
the  yellow  lights. 

Complementary  Colors.  —  To  produce  white  the  simple 
wave  lengths  must  be  present  in  the  right  number  and 
proportion.  Both  theories  assume  that  white  or  gray 
light  is  produced  when  all  of  their  primary  colors  are 
present  in  the  proper  balance.  For  Helmholtz  all  must 
excite  the  retina  at  the  same  time,  while  Hering  asserts 
that  white  is  seen  whenever  both  components  of  either 
of  his  complementary  pairs  of  simple  colors  are  active 
in  the  same  degree,  and  that  they  are  all  present  in  the 
spectrum  in  almost  the  proper  balance  to  neutralize 
each  other.  This  explains  the  fact  mentioned  in  con- 
nection with  the  first  law,  that  spectral  colors  when 
mixed  do  not  give  a  saturated  color  and  that  the  farther 
apart  they  are  in  the  spectrum  the  less  saturated  they 
become.  Colors  farther  apart  are  more  nearly  com- 
plementary, and  so  more  white  is  present  in  the  com- 
pound. The  list  of  wave  lengths  of  colors  that  are 
complementary  is  given  in  Table  I.  It  will  be  seen  that 
no  simple  statement  can  be  made  of  the  relation  of  the 
wave  lengths  of  complementary  colors.  Each  must  be 
determined  for  itself.  As  a  result  of  the  facts  stated 
in  this  law  it  may  be  asserted  that  each  color  has  a 
complement,  that  all  colors  go  in  pairs,  although  the 
colors  in  the  middle  of  the  spectrum  have  non-spectral 
colors  as  their  complements.  In  terms  of  the  four-color 
theory  each  primary  color  has  a  complement  —  green  is 


SENSATION  —  VISION 


123 


Table  I.  —  Table  of  Complementary  Colors  for  Two  Observer: 


Obser\'Er  von  Kries 


Obser\-er  von  FR£Y 


Long  Light  Wave 

Coraplementarj' 

Long  Light  \\'ave 

Complementarj' 

m  MM 

Short  Wave 

in  Mi>J- 

Short  Light  Wave 

656.2 

492.4 

656.2 

485.2 

626 

492.2 

626 

484.6 

612.3 

489.6 

612.3 

483-6 

599-5 

487.8 

599-5 

481.8 

587.6 

484.7 

587.6 

478.9 

579-7 

478.7 

586.7 

478.7 

577.6 

473-9 

577-7 

473.9 

575-5 

469-3 

572.8 

469.3 

572.9 

464.8 

570.7 

464.8 

571-1 

460.4 

569-0 

460.4 

570-4 

440.4 

566.3 

440.4 

570.1 

429-5 

566.4 

429.5 

the  complement  of  red.  blue  of  yellow.  As  each  com- 
bination of  two  colors  is  made  up  of  two  simple  colors, 
there  is  alwa^'.s  a  second  combination  of  two  "colors, 
each  complementary  to  one  member  of  the  first  pair, 
which  when  mLxed  give  gray. 

Color  Blindness.  —  The  phenomena  of  color  blind- 
ness oiler  much  aid  to  an  understanding  of  color  vision. 
Some  three  to  five  per  cent  of  men  and  a  much  smaller 
percentage  of  women  are  found  by  tests  to  be  unable 
to  distinguish  red  and  green.  To  them  reds  and  greens 
look  exactly  alike.  When  the  proper  changes  in  bright- 
ness are  made,  red  and  green  papers  look  gray  and  all 
three  may  be  confused.  The  fact  of  confusion  has  been 
noted  for  a  long  time.  The  chemist  Dalton  furnished 
one  of  the  first  instances  recorded,  and  for  a  long  time 


124  FUNDAMENTALS   OF  PSYCHOLOGY 

the  defect  was  known  as  Daltonism.  It  is  only  recently 
that  fairly  general  agreement  as  to  the  explanation  has 
been  reached.  Young  and  Helmholtz  and  their  fol- 
lowers were  of  the  opinion  that  one  might  be  blind  to 
only  one  color,  one  might  be  red-blind  or  green-blind, 
or  both.  Studies  by  Von  Kries  and  others  who  were 
originally  pupils  of  Helmholtz  convinced  them,  however, 
that  on  the  whole  Hering  was  right  in  his  statement 
that  when  one  of  a  pair  of  complementary  colors  could 
not  be  seen,  the  other  was  also  wanting.  In  brief,  the 
red-blind  individual  is  also  green-blind  and  sees  both 
colors  as  grays.  Still  rarer  are  the  cases  in  which  the 
sufferer  sees  no  colors,  but  only  grays.  One  other  case 
is  rarest  of  all  in  which  the  patient  is  blue-yellow  blind, 
and  can  see  red  and  green,  but  not  blue  or  yellow. 

Peripheral  Vision.  —  Closely  related  to  the  phenomena 
of  color  blindness  is  the  vision  on  the  peripheral  retina 
of  the  normal  eye^  It  may  be  said  that  every  eye  has 
in  it  a  red-green  blind  area,  and  a  totally  color  blind 
area.  If  one  will  look  at  any  color  out  of  the  side  of  the 
eye,  it  will  be  seen  that  the  colors  undergo  a  marked 
change.  One  can  see  the  full  range,  of  colors  only  for 
twenty  or  thirty  degrees  from  the  fovea ;  the  distance 
varies  with  the  individual  and  with  the  diagonal  that 
is  used.  Beyond  that  one  can  see  no  reds  or  greens,  but 
for  ten  degrees  or  so  farther  blues  and  yellows  alone. 
Beyond  that  grays  only  are  perceived.  The  field  of 
vision  for  colors  and  for  grays  extends  much  farther  on 
the  temporal  side  and  below  than  on  the  nasal  side 
and  above.  Of  course  since  light  crosses  in  the  eye,  the 
field  for  color  on  the  retina  is  larger  on  the  nasal  side  and 


SENSATION  —  VISION  1 2  5 

above.  Different  experiments  will  not  ordinarily  show 
that  members  of  the  same  pair  of  colors  vanish  sharply  at 
the  same  point,  since  the  point  of  disappearance  depends 
upon  the  size  of  the  colored  surface,  upon  the  saturation 
and  tone  of  the  color,  upon  the  brightness  of  the  color, 
and  upon  its  contrast  with  the  background,  and  it  is 
very  difficult  to  obtain  standard  stimuH  and  conditions. 
When  all  the  colors  used  have  the  same  values  in  these 
respects,  the  colors  vanish  by  pairs  as  indicated  above. 

These  facts  of  color  blindness  and  of  peripheral  \dsion 
indicate  that  the  four  primary  colors  are  closely  joined 
in  pairs.  A  study  of  the  colors  that  remain  to  the  color 
blind  and  of  the  way  colors  vanish  on  the  periphery  of 
the  eye  is,  then,  an  important  aid  to  the  determination 
of  what  are  the  primary  colors.  That  there  are  four 
colors  rather  than  three  becomes  evident  from  the  fact 
that  first  red  and  green  disappear  and  then  yellow  and 
blue. 

Negative  After-images.  —  Two  other  subordinate 
phenomena  emphasize  the  opposition  between  these 
pairs  of  colors.  These  are  the  negative  after-image 
and  contrast.  One  may  obtain  a  negative  after-image 
if  one  looks  for  several  seconds  at  any  color  and  then 
for  a  couple  of  seconds  at  a  neutral  surface.  The 
negative  after-image  is  a  fainter  patch  of  the  comple- 
mentary color  which  gradually  makes  its  appearance 
upon  the  neutral  surface  and  remains  for  several  seconds. 
The  length  of  time  that  it  lasts  depends  upon  the  in- 
tensity of  the  original  color,  upon  its  duration,  and  the 
extent  of  the  surface  stimulated,  and  upon  the  degree 
of  fatigue  of  the  eye.     If  two  primary  colors  are  present 


126  FUNDAMENTALS   OF   PSYCHOLOGY 

in  the  inducing  stimulus,  the  complement  of  each  will 
be  present  in  the  after-image.  Thus  purple  gives  a 
yellow-green,  orange,  a  greenish  blue  after-image.  The 
complete  explanation  of  this  phenomenon  can  best  be 
discussed  in  connection  with  the  theories  of  color. 
We  may  be  content  here  to  regard  it  as  another  indica- 
tion of  the  fact  that  complementary  colors  stand  in  a 
very  close  relation  to  each  other. 

Contrast.  —  The  laws  of  contrast  may  be  stated  in 
terms  very  similar  to  those  used  for  the  after-imSge, 
different  from  it  only  in  that  one  relation  is  spatial, 
the  other  temporal.  One  has  been  called  successive, 
the  other  simultaneous  contrast  or  induction.  Wher- 
ever a  color  stimulates  the  retina,  a  complementary 
color  is  induced  in  the  surrounding  area.  The  bright- 
ness of  the  induced  color  and  the  size  of  the  halo  depend, 
again,  upon  the  brightness  of  the  color,  its  size,  and 
upon  the  similarity  in  brightness  between  the  color 
and  its  background.  Contrast  colors  can  be  seen  most 
easily  if  a  colored  light  and  a  white  Hght  are  admitted 
to  a  dark  room  and  a  rod  casts  a  gray  shadow  on  the 
colored  surface.  The  shadow  will  appear  in  the  com- 
plement of  the  color.  Thus  shadows  on  the  grass  are 
purple,  those  on  the  snow  in  yellow  sunshine  are  blue, 
etc.  A  gray  strip  of  paper  on  a  colored  surface  also 
takes  on  a  color  complementary  to  the  paper,  but  it  is 
not  so  easily  seen  by  the  beginner.  If  one  will  cover 
the  entire  surface  with  tissue  "paper,  the  contrast  color 
comes  out  clearly.  In  general,  the  rule  holds  that  the 
less  definite  the  contour  between  the  inducing  and  the 
induced   color,    the   more   definite    the   contrast.     The 


SENSATION  —  VISION  1 27 

individual  has  become  so  accustomed  to  seeing  contrast 
colors  that  he  forms  the  habit  of  allowing  for  them^  and 
sees  the  objects  in  the  colors  that  they  would  have 
were  they  alone.  He  has  learned  that  a  gray  strip  of 
paper  looks  red  on  a  green  background  and  sees  the 
gray  that  is  known  to  be  the  real  color  of  the  paper 
in  spite  of  its  appearance.  The  tissue  paper  makes  it 
difficult  to  be  sure  that  the  gray  strip  is  really  a  separate 
object  on  a  colored  surface,  the  habitual  interpretation 
is  not  appHed,  and  the  contrast  color  that  is  really  pres- 
ent on  the  retina  is  seen. 

Summary  of  Facts  of  the  Chromatic  Series.  —  Of 
the  pure  spectral  colors  we  may  assert  that  all  are  com- 
bined from  four  primary  colors,  —  red,  green,  yellow  and 
blue  —  and  that  these  four  colors  are  paired  in  most  of 
their  activities,  red  with  green,  and  yellow  with  blue. 
Each  when  mixed  with  its  complement  gives  gray.  In 
color  bhndness  and  on  the  peripheral  retina,  red  and 
green,  yellow  and  blue,  disappear  together.  When  one  of 
these  colors  stimulates  the  retina,  its  complement  appears 
in  the  after-image,  and  the  complement  also  irradiates 
from  its  surface,  giving  the  contrast  color. 

The  Achromatic  Series.  —  Fewer  statements  can  be 
made  concerning  the  brightness  series.  Unlike  the 
spectral  series,  there  is  no  break  in  the  series  of  grays,. — 
one  may  pass  from  black  to  white  by  a  regular  series  of 
gradations.  Primarily  the  shade  of  gray  is  determined 
by  the  intensity  of  the  external  stimulation.  In  this, 
as  in  colors,  contrast  plays  an  important  part.  A  gray 
is  Hghter  on  a  black  surface  than  it  is  against  a  white 
surface.     Similarly,    the    previous    stimulation   of    the 


128  FUNDAMENTALS   OF  PSYCHOLOGY 

retina  plays  an  important  part  in  determining  the  ap- 
parent brightness.  When  one  has  been  in  a  bright 
light,  grays  seem  darker ;  when  one  comes  from  a  dark- 
ened room  they  seem  at  first  brighter  than  normal. 
This  is  related  to  the  negative  after-image  if  the  preced- 
ing stimulus  is  comparatively  brief.  The  brightnesses 
have  the  same  general  law  of  mixture  as  do  colors. 
Mixtures  of  grays  give  an  intermediate  gray. 

One  fact  that  has  attracted  considerable  attention  is 
that  the  grays,  while  very  complex  in  their  physical 
stimulus,  should  nevertheless  give  a  perfectly  simple 
series  of  sensations.  One  can  obtain  gray,  as  was 
stated  above,  only  by  the  mixture  of  complementary 
colors.  How  the  combinations  of  simple  rays  produce 
white  has  been  a  point  in  dispute  between  the  three- 
color  and  the  four-color  theories.  Helmholtz  held  that 
the  three  primary  colors  combine  to  produce  white, 
and  that  all  three  must  be  present  if  white  is  to  be 
seen.  Hering,  on  the  contrary,  insisted  that  there  was 
a  separate  organ  and  separate  processes  for  white,  that 
all  lights  stimulated  this  organ,  and  that  complementary 
colors  gave  white  simply  because  the  colored  effects 
neutralized  each  other  and  gave  the  white  which  was 
always  present  a  chance  to  be  seen.  Color  blindness 
shows  that  the  assumption  of  Helmholtz  must  be  in- 
correct in  this  respect.  Were  white  a  compound  of 
three  colors,  the  individual,  color  blind  to  green,  when  his 
eye  is  stimulated  by  sunlight,  should  see  the  remaining 
colors  of  the  spectrum,  red  and  blue,  combined  in  purple, 
instead  of  the  gray  that  he  really  does  see.  There 
is  every  evidence  that  the  brightnesses  correspond  to 


SENSATION  —  VISION  1 29 

the  excitation  of  an  independent  organ.  It  is  not  a 
compound  produced  by  the  excitation  of  the  organs  of 
primary  colors. 

The  Duplicity  Theory.  —  One  discovery  of  recent 
years  is  that  there  is  a  different  organ  active  in  seeing 
faint  lights,  from  that  involved  in  ordinary  daylight. 
While  the  organ  for  brightness  is  usually  some  sub- 
stance in  the  cones,  the  rods  are  used  in  seeing  faint 
lights.  The  most  striking  evidence  for  this  is  that  after 
long  adaptation  the  retina  becomes  much  more  sensitive 
to  faint  lights,  from  two  thousand  to  eight  thousand 
times  as  sensitive  after  an  hour  in  a  dark  room.  This 
increased  sensitiveness  does  not  affect  the  fovea,  where, 
as  will  be  remembered,  there  are  only  cones,  but  only 
the  periphery,  where  there  are  rods.  This  can  be  proven 
if  one  will  look  at  a  faint  star  first  directly  and  then 
look  to  one  side  so  that  the  star  may  be  seen  with  the 
periphery  of  the  retina.  It  looks  brighter  on  the  pe- 
riphery. Stars  that  cannot  be  seen  with  the  fovea  may 
be  seen  w^hen  looked  at  indirectly.  This  is  even  more 
easily  demonstrated  if  one  will  use  a  somewhat  larger 
surface.  At  night  a  faintly  illuminated  patch  of  gray 
paper  can  readily  be  seen  out  of  the  side  of  the  eye 
when  it  is  invisible  in  direct  vision.  The  increased  sen- 
sitiveness in  the  rods  is  ascribed  to  the  presence  of 
visual  purple,  which  is  found  only  in  them,  and  which, 
while  lacking  in  daylight,  is  accumulated  after  a  long 
period  in  the  dark. 

The  Purkinje  Phenomenon.  —  Further  evidence  for 
this  independent  rod  vision  comes  out  in  connection  with 
the  third  series  of  phenomena,  the  variation  in  color  with 

K 


130  FUNDAMENTALS   OF  PSYCHOLOGY 

diminution  in  the  intensity  of  a  single  wave  length  of 
light.  As  was  said,  the  spectral  colors  tend  towards 
black  as  the  intensity  is  diminished,  and  all  lose  their 
colors  before  the  light  disappears.  All  Hghts  of  low 
intensity  appear  colorless.  The  point  at  which  the 
colors  disappear  varies  for  the  different  wave  lengths. 
The  reds  on  the  whole  vanish  first  as  the  light  is  dimin- 
ished in  intensity,  while  the  short  wave  lengths  retain 
their  color  at  a  lower  intensity.  If  a  mixture  of  yellow 
and  red  (orange)  be  gradually  reduced  in  intensity,  the 
red  will  disappear  first,  leaving  only  the  yellow  compo- 
nent. The  orange  changes  to  yellow  as  the  light  is 
diminished.  More  important  is  the  fact  that  the 
brightness  of  the  different  parts  of  the  spectrum  is 
differently  affected  by  reducing  the  light.  The  long 
Wave  lengths  are  relatively  bright  in  ordinary  dayhght 
and  the  short  wave  lengths  in  the  twihght.  If  one  com- 
pare the  brightness  of  a  bit  of  blue  paper  and  a  bit  of 
red  paper  in  dayhght  and  the  red  be  brighter  but  nearly 
equal  to  the  blue,  and  then  compare  the  same  bits  in  a 
dark  room,  it  is  found  that  the  blue  will  be  decidedly 
brighter.  This  change  in  relative  brightness  goes  on 
gradually  and  is  marked  when  the  absolute  brightness 
is  so  low  that  no  colors  are  seen.  This  change  in  the 
relative  brightness  of  colors,  known  as  Purkinje's  phe- 
nomenon, is  also  regarded  as  characteristic  of  rod  vision. 
It  again  is  not  observed  on  the  fovea  where  the  rods  are 
lacking  and  cannot  be  detected  in  daylight  on  the  pe- 
riphery of  the  retina  where  the  colors  are  not  seen  but 
where  cones  are  present.  It  is  a  phenomenon  peculiar 
to  the  rods.     It  may  be  phrased  in  the  statement  that 


SENSATION  —  VISION 


131 


the  rods  are  relatively  highly  susceptible  to  stimulation 
by  the  short  wave  lengths,  the  cones  by  the  long  wave 
lengths.  All  of  this  seems  to  indicate  that  there  are 
two  distinct  organs  involved  in  seeing  brightnesses,  the 


fon 

190 

1R0 

170 

160 

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Fig.  45.  —  Chart  showing  relative  brightness  of  red  Hght  in  the  spectrum  of 
gas  light  for  two  protanopes,  S  and  M,  and  for  two  deuteranopes,  St  and  V. 
(From  von  Kries.) 

cones  and  the  rods.  A  brightness  or  gray  seen  with 
the  rods  cannot  be  distinguished  from  a  gray  of  the 
same  brightness  seen  with  the  cones.  The  only  difference 
is  to  be  found  in  the  relative  susceptibility  of  the  two 


132  FUNDAMENTALS    OF   PSYCHOLOGY 

organs  to  different  lengths  of  light  waves,  and  in  the 
possibiKty  of  greatly  increasing  the  sensitivity  of  the 
rods  by  adapting  them  to  darkness. 

The  Different  Forms  of  Color  Blindness.  —  The  dis- 
tinction drawn  between  daylight  and  twilight  vision,  or 
cone  vision  and  rod  vision,  has  proved  very  fruitful  in 
the  interpretation  of  certain  facts  of  color  bhndness. 
In  the  long  controversy  between  Hering  and  Helmholtz 
a  standing  point  of  discussion  was  as  to  whether  there 
was  ever  blindness  to  red  without  also  blindness  to 
green.  Hering  insisted  that  blindness  to  one  was  al- 
ways accompanied  by  bhndness  to  the  other.  Helm- 
holtz regarded  red  and  green  as  independent  colors  and 
asserted  that  one  might  be  blind  to  either  alone.  Ob- 
servations seemed  ambiguous.  Most  cases  lacked  both 
colors,  but  occasionally  careful  examination  indicated 
that  one  color  would  be  seen  more  clearly  than  the 
other.  When  the  twiHght  or  rod  vision  was  discovered, 
it  was  soon  found  that  in  the  eye  of  the  totally  color 
blind  only  the  rods  were  active.  The  patient  could 
see  much  better  in  twiHght  than  in  ordinary  daylight, 
the  relative  brightness  of  spectral  waves  was  the  same 
as  that  of  the  normal  individual  in  twilight,  and  it  was 
shown  in  a  number  of  cases  that  he  was  totally  bHnd 
in  the  fovea,  where,  as  has  been  said,  there  are  no  rods. 
In  certain  cases  the  bUndness  in  the  fovea  was  not 
noticed,  but  von  Kries  argues  that  this  was  probably 
due  to  the  difficulty  in  making  observations.  Not  all 
would  agree  that  every  case  of  color  blindness  is  due  to 
lack  of  function  of  the  cones,  but  certainly  many  are. 

In  the  appHcation  of  this  discovery  to  the  cases  of 


SENSATION  —  VISION 


133 


partial  color  blindness,  measurement  of  the  brightness 
values  of  a  number  of  individuals  indicated  that  the 
difference  between  the  two  types,  called  by  Helmholtz 
the  red  blind  and  the  green  blind,  could  be  traced  to  the 
dominance  of  twiHght  brightness  values,  or  to  the  domi- 
nance of  dayhght  values.  Both  types  were  defective  in 
both  red  and  green,  but  as  the  red  bHnd  saw  the  spectrum, 


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Fig.  46.  —  Brightness  of  prismatic  spectrum  of  gas  light  for  total  color  bliad 

,  and  for  twilight  vision  of  normal  eye Comparison  with  Fig.  45  shows 

that  both  have  the  same  value  as  the  protanope.     (From  von  Kries.) 

the  long  wave  lengths  were  much  darker  and  so  the  reds 
were  not  noticed.  For  the  other  type  the  long  wave 
lengths  were  brighter  and  they  were  more  Hkely  to  see 
the  reds  than  the  greens.  To  avoid  the  ambiguities  of 
the  older  terms  von  Kries  has  suggested  that  those 
individuals  who  see  the  spectrum  in  the  relative  bright- 
ness values  of  normal  individuals  in  dayHght  be  called 
deuteranope,  those  who  see  it  in  twilight  values  shall 
be  called  protanope.     The  brightness  values  are   the 


134 


FUNDAMENTALS   OF   PSYCHOLOGY 


I 


same  for  the  protanope,  for  the  totally  color  bHnd  and  for 
the  twilight  vision  of  the  normal  eye,  and  also  for  the 
deuteranopes,  the  normal  eye  in  daylight,  and  the  pe- 
riphery of  the  normal  eye,  as  may  be  seen  from  the 
accompanying  charts  from  von  Kries.  All  this  argues 
for  two  kinds  of  brightness  vision,  one  by  the  cones, 
the  other  by  the  rods.  While  the  actual  sensations  of 
gray  given  by  the  two  are  not  to  be  distinguished,  the 
secondary  characteristics  are  markedly  different. 


100 

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70 
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Fig.  47.  —  Brightness  of  the  gas  light  spectrum  for  the  peripliery  of  the  normal 
eye ,  and  for  protanope .     (From  von  Kries.) 

Temporal  Phenomena  in  Vision.  —  The  characteristics 
of  a  color  depend  in  many  ways  upon  the  duration  of 
the  color  stimulus.  Stimuli  do  not  produce  their 
maximum  effect  at  once  nor  does  the  color  cease  at  once 
with  the  excitation.  There  is  always  a  rise  to  full  effect 
and  a  gradual  disappearance.  The  course,  as  has  been 
shown  by  Miss  Bills,  is  different  for  each  of  the  colors, 
both  for  the  period  required  to  attain  its  maximum, 
and  for  the  period  of  decline.  The  curve  varies  for  each 
color  and  for  the  different  intensities  of  the  color.  At 
the  lowest  intensity  used,   the  order  was  yellow,  red. 


SENSATION  —  VISION  135 

green,  and  blue  ;  for  the  medium  intensity  it  was  yellow, 
green,  blue,  red ;  and  for  the  highest  intensity,  yellow, 
red,  green,  with  blue  undetermined.^  These  results 
were  obtained  in  the  dark.  They  may  be  different  for 
dayHght  conditions.  When  the  sensation  reaches  its 
maximum,  it  begins  at  once  to  diminish  in  intensity,  at 
first  rapidly,  and  then  very  gradually  until  all  colors 
disappear.  This  gradual  loss  of  color  can  be  easily 
demonstrated  if  one  will  but  gaze  fixedly  at  a  small 
square  of  color.  The  disappearance  of  the  color  of  the 
glass  when  colored  glasses  are  worn  illustrates  the  same 
phenomenon.  Black  and  white  also  show  the  same 
tendency.  The  rate  of  adaptation  varies  with  the 
color,  so  that  one  component  after  another  may  vanish. 
After  the  stimulus  is  removed,  the  excitation  con- 
tinues for  a  moment  to  be  of  the  same  quality  as  the 
original,  and  then  gradually  dies  out.  This  persistence 
is  called  the  positive  after-image.  The  dying  out  cor- 
responds to  the  period  of  rise  of  stimulation.  Both 
may  be  regarded,  and  are  regarded  in  all  theories,  as  an 
expression  of  the  inertia  of  the  color  processes.  They 
require  time  to  start  and  to  stop.  For  a  fraction  of  a 
second  the  color  or  gray  persists  in  approximately  full 
brightness.  It  is  this  fact  that  makes  possible  the  mix- 
ture of  colors  on  rotating  disks.  The  excitation  of  one 
color  persists  during  the  excitation  of  the  retina  by  the 
other.  For  practical  purposes  the  effect  is  the  same  as 
if  both  lights  were  active  at  the  same  time,  and  the 
brightness  effect  produced  is  the  average  of  all  the  lights 
that  are  stimulating  the  eye  during  the  period.     If  the 

^  Psychological  Review,  vol.  xxii,  pp.  126  f. 


136  FUNDAMENTALS   OF  PSYCHOLOGY 

rotation  is  less  rapid,  one  obtains  a  rapid  fluctuation  in 
brightness,  the  flicker.  Of  practical  importance  is  the 
fact  that  the  flicker  disappears  at  a  less  rapid  rate  of 
rotation  if  the  brightness  of  the  colors  is  the  same  than 
if  they  are  different.  This  flicker  effect  has  been  taken 
advantage  of  in  the  measurement  of  the  brightness  of 
different  colors,  a  problem  that  makes  difficulties  for 
ordinary  photometric  methods. 

Aside  from  this  positive  after-image,  if  one  gives  but 
a  single  stimulus  of  relatively  short  duration,  it  will  be 
noticed  that  there  are  at  least  two  other  images  suc- 
ceeding the  first.  After  a  momentary  dark  period  there 
comes  a  complementary  after-image,  usually  with  an 
added  slightly  bluish  hue.  After  another  dark  interval, 
an  image  of  the  same  color  as  the  first  and  usually  fainter 
appears,  to  be  followed  by  another  dark  period.  In- 
cluding the  dark  periods  which  look  like  black  it  is 
possible  under  favorable  conditions  to  see  six  different 
images  following  a  colored  sector  on  a  slowly  rotating 
disk.  These  images  are  an  expression  of  the  fact  that 
the  retina  responds  rhythmically,  that  when  a  retinal 
excitation  is  started  it  rises  and  falls  in  its  excitation  in 
a  regular  order.  The  second  of  the  images  mentioned 
above  is  assumed  to  be  due  to  the  delayed  excitation  of 
the  rods,  the  third  to  a  renewal  of  the  excitation  of  the 
brightness  organ  of  the  cones. 

Interesting  also  is  the  fact  that  it  is  possible  to  excite 
colors  as  an  after-effect  of  brightness.  If  one  will  look 
for  half  a  second  or  so  at  the  setting  sun  and  then  for  a 
time  watch  the  after-image  as  projected  against  a  neu- 
tral surface,  one  will  observe  a  slow  succession  of  colors 


SENSATION  —  VISION  1 3  7 

and  grays  that  will  last  for  several  minutes.  Helm- 
holtz  gave  the  order  as  white,  red,  green,  red,  blue,  with 
the  eyes  open.  One  notes  in  this,  too,  that  the  color  of 
an  image  depends  upon  the  character  of  the  background. 
It  will  have  a  different  color  with  the  eyes  open  and  with 
the  eyes  closed.     When  the  eyes  were  closed,  Helmholtz 


Fig.  48.  —  Benham  disk. 

found  the  order  to  be  blue,  green,  yellow.  It  will 
also  be  noticed  when  a  black  and  white  disk  is  revolving 
slowly  that  a  series  of  faint  colors  seems  to  follow  the 
edge  of  the  black  sector.  Similar,  too,  in  explanation 
is  the  color  produced  when  a  white  disk  with  concentric 
rings  of  black  is  rotated.  If  a  disk  similar  to  that  in 
Figure  48  is  rotated  slowly,  the  inner  ring  appears  pur- 
plish, the  outer  greenish.     The  explanation  of  all  these 


138  FUNDAMENTALS   OF   PSYCHOLOGY 

phenomena  is  somewhat  uncertain,  but  seems  to  fit  best 
with  the  assumption  of  Helmholtz  that  in  some  way  the 
color  processes  are  excited  by  the  black  and  white  and 
that  the  different  colors  die  out  at  different  rates  and 
so  one  color  will  predominate  at  one  time,  another  at 
another. 

The  Spatial  Phenomena  of  Vision.  —  Just  as  the 
visual  excitation  is  not  limited  to  the  actual  duration 
of  the  stimulus,  its  influence  is  also  not  limited  to  the 
area  stimulated,  but  extends  about  it  in  all  directions 
to  varying  extents.  A  series  of  facts  can  be  adduced  to 
demonstrate  this. 

1.  Bright  colors  always  look  larger  than  dark  ones. 
A  white  square  on  a  black  ground  always  looks  larger 
than  a  black  square  on  a  white  ground.  In  each  case 
the  white  stimulus  spreads  at  the  expense  of  the  black. 
Still  more  striking  is  the  apparent  increase  in  the  size 
of  the  filament  of  the  electric  light  when  it  glows  as 
compared  with  its  size  when  cold. 

2.  A  number  of  small  surfaces  of  two  or  more  colors 
when  in  juxtaposition  fuse  into  a  color  identical  with 
that  given  by  the  same  colors  when  mixed  by  rotation. 
Each  color  extends  beyond  the  area  stimulated,  and 
these  extensions  overlap  to  produce  a  continuous  color 
of  the  average  hue  and  brightness  of  all.  The  over- 
lapping in  space  is  similar  to  the  overlapping  in  time  in 
mixtures  produced  by  rotating  disks.  In  many  fabrics 
it  will  be  noticed  that  the  dominant  color  seen  at  a  dis- 
tance is  a  mixture  of  a  number  of  threads  of  different 
colors. 

3.  There  is  a  spatial  extent  of  colors  that  is  too  small 


SENSATION  —  VISION  I39 

to  be  observed,  just  as  there  is  a  temporal  and  intensive 
limen.  Colored  objects  at  a  distance  lose  their  color, 
and  the  minimum  size  varies  with  the  color.  The 
colors  disappear  before  the  brightness.  Several  bits  of 
color,  each  too  small  to  be  seen  alone,  give  color  when 
near  each  other.  This  may  be  explained  by  the  exten- 
sion of  the  stimulus  on  each  small  surface  to  the  others 
about  it  until  the  mutual  overlapping  increases  the 
stimulus  of  each  surface  to  the  point  where  it  may  be 
seen. 

4,  In  large  degree,  size,  duration,  and  intensity  are 
interchangeable.  More  intense  lights  seem  larger,  seem 
to  last  longer,  and,  vice  versa,  within  Hmits  larger  sur- 
faces and  longer  exposures  seem  to  give  more  intense 
stimulations. 

These  various  phenomena  are  to  be  explained  by  the 
spread  of  the  effects  of  the  excitation  in  the  retina,  either 
by  a  spread  of  the  chemical  effects  from  one  unit  to 
another,  or  by  a  spread  of  nervous  impulse  from  the 
cones  or  rods  stimulated  to  neighboring  ones  through 
the  connecting  neurones  just  inside  the  layer  of  rods 
and  cones.  (See  p.  112.)  Contrast  is  due  to  a  similar 
phenomenon,  but  has  been  described  above,  and  the 
explanation  may  best  be  left  to  the  discussion  of  the 
various  theories,  as  the  induction  of  a  complementary 
color  introduces  a  new  principle. 

The  Helmholtz  Theory.  —  A  brief  statement  of  the 
more  important  theoretical  explanations  of  color  may 
serve  as  a  review  of  the  facts.  The  first  of  the  modern 
theories  was  formulated  by  Thomas  Young,  an  English 
physicist,    and    expanded   by   Helmholtz.     It   assumes 


140  PUNDAIVIENTALS  OF  PSYCHOLOGY 

that  there  are  three  separate  organs  in  the  retina,  that 
one  of  these  is  affected  most  strongly  by  red,  another 
by  green,  and  a  third  by  blue  or  indigo.  When  all  three 
are  excited  at  once,  white  is  produced.  Red  and  green 
when  stimulated  together  give  rise  to  yellow.  All  the 
other  colors  are  produced  by  the  mixture  of  the  effects 
of  two  or  all  three  of  the  organs.  After-images  are  due 
to  the  fatigue  of  some  of  the  organs  and  the  response  of 
those  remaining  when  white  light  falls  upon  the  retina. 
Contrast  is  an  illusion  of  judgment.  The  facts  are  out 
of  harmony  with  the  theory  on  all  but  one  point,  i.  Yel- 
low cannot  be  a  compound  color,  since  yellow  may  be 
seen  where  both  its  assumed  components  are  lacking, 
on  the  periphery  of  the  retina  and  by  the  color  blind. 
2.  The  same  objections  hold  against  regarding  white 
as  a  compound.  It,  too,  can  be  seen  where  none  of  its 
components  is  present.  3.  The  explanation  of  after- 
images falls  with  the  abandonment  of  the  theory 
that  white  is  a  compound  color.  4.  Contrast  is  not 
an  illusion  of  judgment,  as  it  is  most  easily  noticed 
where  one  is  not  aware  that  the  inducing  color  is 
present.  The  only  possible  remnant  of  the  Helmholtz 
theory  is  its  explanation  of  color  mixing,  and  the 
colors  that  it  chooses  as  primary  do  not  meet  any  of 
the  physiological  tests. 

The  Hering  Theory.  —  The  Hering  theory  asserts  that 
there  are  two  pairs  of  primary  colors  with  the  elements 
in  each  pair  opposed,  and  an  independent  brightness 
organ.  The  theory  assumes  that  each  pair  of  colors 
is  produced  by  antagonistic  changes  in  the  same  organ. 
One  organ  gives  rise  to  red  and  green,  a  second  to  blue 


SENSATION  —  VISION  14I 

and  to  yellow,  and  a  third  to  the  brightnesses,  black  and 
white.  The  antagonistic  processes  are  said  to  be  anab- 
olism  and  catabolism,  the  upbuilding  of  the  organ  and 
its  deterioration.  Green,  blue,  and  black  induce  anab- 
olism,  the  others  catabolism.  Complementariness  is 
explained  by  the  fact  that  members  of  the  same  pair 
of  colors  tend  to  induce  opposed  processes  in  the  same 
degree  and  so  produce  no  effect.  When  the  tendency  of 
green  to  produce  anabolism  and  of  red  to  cause  catabo- 
lism are  equally  strong,  no  change  in  the  organ  results. 
Since  all  wave  lengths  stimulate  the  brightness  organ, 
gray  is  seen,  and  seen  alone,  when  the  colors  cancel  each 
other.  Color  blindness  is  due  to  an  absence  of  one  or 
more  of  the  organs.  The  red-green  organ  is  most  fre- 
quently lacking.  This  follows  from  the  fact  that  red- 
green  blindness  is  most  frequent  and  also  that  red  and 
green  are  least  -widely  distributed  on  the  retina.  In 
total  color  blindness  the  yellow-blue  organ  has  not 
developed,  the  black-white  organ  alone  is  present. 
Positive  after-images  are  explained  as  due  to  a  continued 
action  of  the  organ  after  the  stimulus  has  ceased.  In 
the  negative  after-image  anabolism  is  followed  by  catab- 
olism since  the  excess  material  accumulated  by  the 
retinal  excitation  tends  to  disappear  as  the  light  ceases 
to  act  and  the  tissues  return  to  their  normal  balance. 
Similarly,  catabolism  is  followed  by  anabolism  as  the 
tissues  are  restored  to  their  normal  balanced  state. 
Contrast  is  due  to  one  process  inducing  its  opposite  in 
contiguous  areas.  Excessive  anabolism  in  a  stimulated 
area  is  at  the  expense  of  the  nourishment  of  the  other 
adjoining  areas,  and  catabolism  results  there. 


142  FUNDAMENTALS    OF   PSYCHOLOGY 

Criticism  of  the  Hering  Theory.  —  The  most  impor- 
tant objection  to  the  Hering  theory  is  its  assumption 
that  the  opposed  processes  are  anabolism  and  catabo- 
lism.  Nowhere  in  the  bodily  structures  is  anabolism 
induced  by  stimulation.  If  the  exact  change  be  left 
indefinite,  be  regarded  as  a  reversible  chemical  process 
as  Miiller  and  von  Kries  have  suggested,  nothing  would 
be  lost  in  adequacy  of  explanation  of  the  phenomena 
and  much  is  gained  in  credibility.  A  second  minor 
objection,  made  by  Miiller,  is  that  it  is  inconsistent  to 
assume  that  the  opposed  processes  cancel  each  other  in 
the  color  organs,  while  in  the  black-white  organ  they 
give  a  sensation,  the  neutral  gray  of  the  rested  eye. 
Miiller  suggests  that  the  retinal  processes  really  cancel 
each  other,  so  that  when  there  has  been  no  excitation  for 
a  long  time  the  retina  gives  no  sensation,  but  that  the 
cortical  cells,  the  central  organ  for  vision,  produce  the 
gray.  As  evidence  for  this  he  cites  the  fact  that  the 
blind,  if  not  blind  from  birth,  always  see  this  gray, 
and  that  a  spot  of  gray  is  seen  where  even  a  small  area  of 
the  retina  has  been  destroyed. 

The  Ladd-Franklin  Theory.  —  A  recent  theory  of 
Mrs.  Ladd-Franklin  gives  an  explanation  of  color 
in  terms  of  evolution.  She  assumes  that  primitive 
vision  in  animals  is  rod  vision  which  gives  differences  of 
brightness  only.  Later  cones  develop  and  with  them 
comes  the  appreciation  of  colors.  Within  the  cones 
there  is  also  a  development.  First  appear  substances 
sensitive  to  blue  and  yellow  alone,  then  the  substance 
sensitive  to  yellow  divides  into  two,  one  sensitive  to 
red  and  the  other  to  green.     Each  more  evolved  organ 


SENSATION  —  VISION  143 

may  act  as  a  whole  to  give  its  original  sensation.  The 
cone  when  stimulated  as  a  whole  gives  brightness,  the 
red  and  green  acting  together  give  yellow.  The  color- 
blind eye  is  an  undeveloped  eye.  In  red-green  blind- 
ness the  yellow  substance  has  not  yet  subdivided,  in 
total  color  blindness  the  cones  act  only  as  rods.  While 
very  ingenious,  its  choice  of  primary  colors  is  open  to 
all  of  the  objections  to  the  Helmholtz  theory,  and  it 
fails  to  recognize  the  differences  between  rod  vision  and 
cone  vision  as  seen  in  the  Purkinje  phenomenon  or  to 
explain  them  in  an  adequate  manner. 

In  the  maze  of  theories  certain  essentials  must  not 
be  lost  sight  of.  i.  There  are  four  primary  colors, 
distinguished  from  the  others  by  the  fact  that  they 
vanish  without  change  of  quality  as  they  are  moved 
outward  to  the  periphery.  2.  These  four  colors  are 
arranged  in  pairs,  red  with  green,  blue  with  yellow. 
The  pairs  cancel  when  mixed  in  suitable  proportions ; 
one  induces  the  other  as  an  after-image  and  excites  the 
other  on  the  surrounding  areas  of  the  retina.  3.  There 
is  an  independent  brightness  which  is  present  in  all 
colors  and  is  seen  alone  when  the  colors  cancel  each 
other,  at  low  intensities  of  light,  and  where  the  color 
organs  are  lacking.  Physiologically  we  must  assume 
an  organ  for  each  pair  of  colors.  For  this  the  Hering 
theory  as  modified  by  von  Kries  is  as  acceptable  as  any. 
That  means  a  single  organ  for  each  pair  and  in  each 
organ  opposed  chemical  processes.  The  exact  nature  of 
the  processes  must  be  left  undecided.  To  this  must 
be  added  the  acceptance  of  a  distinction  between  rods 
and   cones   as   organs   for   brightness.     They   give   the 


144  ■        FUNDAMENTALS    OF   PSYCHOLOGY 

same  sensations  of  brightness,  but  the  rods  are  more 
sensitive  absolutely  and  are  also  relatively  more  sen- 
sitive to  the  short  wave  lengths ;  the  cones  more  sensi- 
tive to  the  long. 

GENERAL  REFERENCES   FOR   COLOR 

Von  Kries:    Die   Gesichtsempfindung.     Nagel's  Handbuch  d. 

Physiologic,  vol.  iii,  pp.  109-279. 
Myers'  Experimental  Psychology,  chaps,  vi,  vii. 
L.iDD-WooDWORTH :    Elements  of  Physiological  Psychology,  pp. 

182-195,  320-344. 
Howell:  Physiology,  pp.  298-358. 

TiTCHENER :  Experimental  Psychology,  vol.  i,  pt.  ii,  pp.  1-50. 
Mrs.  Ladd-Franklin  :  Article  on  Color,  Dictionary  of  Philosophy 

and  Psychology. 
Greenwood:   Physiology  of  the  Special  Senses,  pp.  86-214. 
Parsons  :  Color  Vision. 


J 


CHAPTER  V 
SENSATION,  AUDITION,  TOUCH,  ETC.     WEBER'S  LAW 

The  auditory  sensations  stand  next  to  the  visual, 
both  in  complexity  and  in  importance  for  behavior 
and  mental  life  in  general.  We  can  approach  them 
from  three  different  sciences  and  obtain  an  entirely 
different  set  of  phenomena  in  each.  Physically,  sound 
is  vibration  in  the  air;  physiologically  it  is  oscillation 
of  some  delicate  membrane  in  the  ear;  psychologically 
it  is  the  series  of  sensations,  the  material  of  music  and 
human  speech  on  the  one  hand,  and  the  series  of  noises 
and  unorganized  sounds  on  the  other.  The  physical 
processes  consist  of  longitudinal  oscillations  that  pro- 
ceed outward  concentrically  from  the  vibrating  body. 
These  oscillations  may  be  superimposed  upon  one 
another,  making  waves  of  great  varieties  of  complexity, 
but  always  analyzable  into  their  simple  elements. 
The  rates  that  can  be  heard  range  from  1 6  or  so  to  from 
30,000  to  50,000  per  second. 

The  Structure  of  the  Ear.  —  The  organ  that  translates 
these  vibrations  in  the  air  into  nerve  processes  is  the  ear. 
The  ear  is  composed  of  three  parts :  the  external  ear, 
consisting  of  the  pinna,  commonly  called  the  ear,  and 
the  external  auditory  meatus  or  tube  that  runs  into  the 
head;  the  middle  ear,  an  enlarged  cavity  in  the  skull 
L  145 


146 


FUNDAMENTALS   OF  PSYCHOLOGY 


separated  from  the  external  by  the  membrane  of  the 
tympanum  or  drum ;  and  the  internal  ear,  a  labyrinthine 
cavity  between  the  middle  ear  and  the  brain  where  the 
vibrations  are  translated  into  nervous  impulses.  The 
external    ear    needs    no    description.     The    outer    ear 


Fig.  49.  —  Schematic  section  of  the  ear ;  M  and  G,  external  ear ;  P,  middle 
ear  with  small  bones ;  S,  cochlea ;  B,  semicircular  canal ;  A .  auditory  nerve ; 
R,  Eustachian  tube.  To  give  a  sectional  view  the  cochlea  is  displaced  90°.  Its 
apex  should  be  turned  toward  the  observer.  (From  Calkins,  after  Martin- 
Czermak.) 

probably  has  some  influence  in  collecting  the  vibrations 
in  the  air  and  turning  them  into  the  external  meatus. 
The  meatus  itself  is  curved  slightly  and  thus  reduces 
to  a  minimum  the  probability  of  injury  to  the  membrane 
of  the  tympanum. 

The  important  structures  of  the  middle  ear  are  the 
membrane  of  the  drum,  three  small  bones  that  stretch 


SENSATION AUDITION 


147 


across  the  ca\dty  of  the  middle  ear,  and  the  membrane 
which  with  the  plate  of  the  last  of  the  bones  fills  the  oval 
window  of  the  inner  ear.  The  series  of  bones  consist 
of   the  malleus,  incus,  and   stapes,  named   from  their 


Fig.  50. — Tympanum  and  small  bones  seen  from  within  the  middle  ear. 
I,  anvil;  2,  suspensor>' ligament  of  hammer;  4,  head  of  hammer;  7,  tendon  of 
tensor  tympani ;  8,  foot-piece  of  stirrup  that  fits  into  the  oval  window ;  10,  han- 
dle of  hammer  or  manubrium ;  1 1,  tensor  tympani ;  1 2,  membrane  of  the  drum ; 
13,  Eustachian  tube. 

shapes,  which  resemble  a  hammer,  anvil,  and  stirrup, 
respectively.  The  handle  of  the  hammer  is  fastened 
to  the  inner  surface  of  the  membrane  of  the  tympanum, 
the  head  is  jointed  into  the  top  surface  of  the  anvil, 
not  unhke  a  large  molar  tooth  in  shape,  and  is  hung 


148 


FUNDAMENTALS   OF  PSYCHOLOGY 


Fig.  51. 
die  ear.  M 
stirrup. 


-  The  bones  of  the  mid- 
hammer:    /,  anvil;    S, 


by  a  ligament  frorr    the  tc; 
of  the  cavity  of  tt  3  midcl  . 
ear.     The  stirrup  is  attached 
by  a  delicate  carti!  ge  to  a 
process  of  the  anvil   not  un 
like  one  of  the  roo  s  of  t]i 
tooth.     The  memb]  mes  an. 
the  bones  swing  together  o. 
the  ligament  as   a  fulcrum. 
When  the  air  vibrations  im 
pinge   on  the  menbrane   o 
the  drum,  it  swings  inward, 
carrying  the  hammer  and  the  other  bones  wi  h  it,  an 
the  foot  of  the  stirrup  pushes  against  the  endcl)inph  ; 
the  inner  ear,  and   sets  that  in  vibration  al  o.     Tw^ 
muscles  prevent  movements  strong  enough  t(    ruptur 
either  membrane.     One, 
the  tensor  tympani,  ex- 
tends   sidewise    from    a 
bony  canal  inside  of  the 
tympanum    and    is    in- 
serted in  the  head  of  the 
hammer;    the  other,  the 
stapedius,    extends  from 
a  tube  in  the  lower  inner 
wall  of  the  cavity  and  is 
inserted  by  a  long  liga- 
ment in  the  head  of  the         Fig.  52.— illustrates  the     ^  ; 
stirrup  _near_  where   the     f^'T, 'rir,.r„M     V- 

anvil      is      joined      to     it.        2,  the  long  process  of  the  . 
rpi        ,  ,  stirrup;  a-i,  the  axis  of  rota 

ine   two  muscles  oppose       Howell's  "Text-book  of  Phj     -I  ,: 


SENSATION 


AUDITION 


149 


each  other.  The  tensor  tympani  tends  to  draw  the 
drum  head  inward,  the  stapedius  to  draw  the  stirrup 
foot  away  from  the  oval  window  toward  the  drum 
head.  When  both  contract,  the  entire  vibrating 
mechanism  is  held  firm  and  prevented  from  making 
too  violent  oscillations. 

The  membrane  of  the  drum, 
by  lirtue  of  its  conical  shape, 
the  arrangement  of  the  fibres 
that  compose  it,  and  the 
weighting  on  one  side  only, 
has  no  tone  of  its  own,  re- 
sponds to  all  vibration  rates 
impartially,  and  so  trans- 
mits all  tones,  whatever  their 
pitch,  with  approximately 
equal   strength.     In    travers-        Fig.   53.  —  To  illustrate  the 

,■,  •JJ1  J. -I  lever  action  of  the  ear  bones,     m, 

mg    the    middle    ear,    the    am-     the  hammer;   e,  the  anvil;    a,  the 

pKtude   of  the  waves  is   de-    ^^^''^  P^^^^ess  of  the  anvil  which 

...  abuts  upon  the  wall  of  the  middle 

creased     and     their     mtensity     ear  and  serves  as  point  of  rotation  ; 

increased  very  greatly.  This  -^  '^^'^r'  "-^'  ""'  '°^' 
change    takes    place  in   two 

ways.  First  the  area  of  the  oval  window  is  much 
smaller  than  the  area  of  the  drum,  so  that  the  energy 
is  more  concentrated.  Second,  as  can  be  seen  in  Fig- 
ure 53,  the  lever  arm  formed  by  the  hammer  of  the 
handle  has  a  greater  effective  length  than  that  formed 
by  the  process  of  the  anvil  to  which  the  stirrup  is 
attached.  Sound  waves,  then,  traverse  the  oscillating 
mechanism  of  the  middle  ear  with  rate  or  pitch  un- 
changed but  with  intensity  increased  twenty  to  thirty 


l^O 


FrXD.\MENTALS    OF   PSYCHOLOGY 


times  and  -with,  a  considerable  diminution  in  amplitude. 
An  essential  mechanism  for  making  possible  the  xibra- 
tion  of  the  dnim  and  for  protecting  it  against  rupture  due 


Fig.  54-  —  ^ --- '■ .  ;>>.-.:.  .:  ;-.  ......._  _:  _  ._:;    (U,  cochlear  duct; 

gsp,  sptrai  ganglion:  misp,  membrane  spiralis  ( basilar  membrane):  mr,  Reiss- 
ner's  membrane ;  j»,  oocfalear  Detve ;  set,  scab  t>-mpani ;  scr,  scala  vesubuli. 
(From  Ruber,  after  Sobotta.) 


to  difference  in  air  pressure  in  the  outer  air  and  that 
within  the  ear  is  the  caning  into  the  throat  pro\'ided 
by  the  Eustachian  tube.     This  senses  to  keep  the  pres- 


SENSATION  —  AUDITION  I5I 

sure  of  the  air  in  the  middle  ear  approximately  equal  to 
that  in  the  outside  world.  The  act  of  swallo^iving  opens 
the  tube  and  permits  the  interchange  of  air. 

The  Cochlea.  —  The  inner  ear.  or  lab}Tinth,  is  filled 
with  lymph.  It  has  two  openings  into  the  middle  ear, 
both  closed  by  delicate  membranes.  One  we  have 
mentioned  as  recei\'ing  the  foot  of  the  stirrup.  The 
joint  is  made  watertight  by  a  membrane.  This  is  the 
oval  window.  The  other,  a  little  below  the  oval  window, 
is  closed  by  a  simple  membrane.  From  its  shape  it  is 
called  the  round  window.  We  may  distinguish  two 
parts  of  the  iimer  ear.  the  cochlea  and  the  labyrinth 
proper,  —  the  semicircular  canals,  utriculus,  and  sacculus. 
As  the  cochlea  alone  is  concerned  in  hearing,  a  descrip- 
tion of  the  other  structures  may  be  left  over.  In  essen- 
tials the  cochlea  is  a  tube  di\-ided  up  its  middle  by  a 
partition  of  bone  and  membrane.  One  side  of  the  par- 
tition is  closed  by  the  oval  window,  the  other,  or 
lower,  by  the  round  window.  The  tube  is  wound  two 
and  a  hah  times  about  a  central  column  of  bone,  the 
modiolus.  The  cochlear  ner\-e,  the  nerve  of  hearing, 
enters  the  centre  of  the  modiolus,  and  ascends  to  the 
top.  gi\'ing  off  a  spiral  band  of  nerves  from  the  bottom  to 
the  top  of  the  cochlea.  It  enters  through  the  spiral  ridge 
of  bone,  the  lamina  spiralis,  and  ends  in  close  connection 
with  cells  tipped  with  hairs  on  and  about  the  basilar 
membrane.  This  basilar  membrane,  together  with  the 
lamina  spiralis,  constitutes  the  di\-iding  partition  of  the 
cochlear  tube.  If  one  looks  at  a  section  of  the  cochlea, 
one  sees  five  or  six  sections  of  the  tube  TFig.  54).  In 
each  of  these  there  are  three  di\'isions,  the  cross  sections 


152  FUNDAMENTALS    OF   PSYCHOLOGY 

of  canals.  The  upper  one  in  the  figure  is  called  the  scala 
vestibuli,  the  staircase  of  the  vestibule,  since  it  con- 
nects directly  with  the  vestibule  and  the  oval  window. 
A  small  triangular  canal  is  divided  off  by  the  basilar 
membrane  and  a  delicate  membrane  above  it,  Reissner's 
membrane.  This  is  the  cochlear  canal.  Below  the 
basilar  membrane  is  the  scala  tympani  which  connects 
with  the  round  window.  The  vibrations  of  the  stirrup 
are  transmitted  to  the  lymph  through  the  oval  window, 
and  ascend  to  the  top  of  the  cochlea  by  the  scala  ves- 
tibuli.  At  the  apex  is  an  opening  between  the  scala 
vestibuli  and  the  scala  tympani,  which  is  supposed  to 
permit  the  vibrations  to  pass  from  one  to  the  other. 
The  delicate  membrane  of  the  round  window  permits 
the  liquid  to  vibrate  as  it  could  not  were  there  but  one 
opening  to  the  cavity  filled  with  liquid.  By  virtue  of 
these  connections,  the  liquid  in  the  cochlea  \dbrates  at 
the  rate  of  the  sound  wave  in  the  air,  with  greater  force 
but  with  less  amplitude. 

The  Sensation  of  Tone.  —  The  problem  for  the  theory 
of  hearing  is  how  the  vibrations  in  this  liquid  in  the 
cochlea  may  excite  the  auditory  nerve.  To  answer 
this  question  we  must  turn  to  a  consideration  of  the  facts 
of  auditory  sensation.  The  qualities  of  tone  run  in  a 
single  line  from  low  to  high.  Slow  vibrations  give  low 
tones,  rapid  vibrations  high  tones.  The  lowest  tjynes 
that  can  be  heard  vary  from  about  twelve  to  sixteen 
per  second.  The  upper  limit  was  given  by  Galton  at 
50,000,  by  Preyer  at  40,000,  Bruner  from  22,000  to 
43,000  for  different  individuals,  while  Edelmann  asserts 
that    some    individuals    can    hear    50,000    vibrations. 


SENSATION  —  AUDITION  1 53 

The  lower  tones  are  determined  by  means  of  large  forks, 
the  upper  usually  by  a  whistle  \\ith  very  short  barrel, 
first  de\'ised  by  Galton,  of  which  a  new  and  more  accu- 
rate model  has  recently  been  made  by  Edelmann.  The 
intermediate  tones  increase  regularly  in  pitch. 

The  accuracy  with  which  the  pitch  of  tones  may  be 
distinguished  varies  markedly  with  the  absolute  pitch. 
Tones  in  the  middle  range  can  be  discriminated  much 
more  easily  than  very  high  tones  or  very  low  tones. 
From  64  to  1024  V  D,  one  can  distinguish  differences 
as  small  as  to  0.3-0.2  of  a  vibration.  Above  or  below 
this,  tones  must  be  much  more  different  to  be  distin- 
guished. At  32  and  2048  V  D  the  addition  of  0.4  of  a 
\dbration  can  just  be  noticed,  and  for  very  high  and  very 
low  tones  many  vibrations  may  be  added  before  a  dif- 
ference is  noted.  One  can  distinguish  tones  differing  by 
these  amounts  and  even  say  which  is  higher  and  which 
lower.  On  the  basis  of  these  experiments  by  Preyer, 
Luft  ^  and  ^Vlax  Meyer,^  it  has  been  estimated  that  one 
can  distinguish  approximately  11,000  different  pitches. 

Within  the  range  of  audible  tones  there  seem  to  be 
critical  points  similar  in  a  way  to  the  critical  points  in 
the  spectrum.  In  the  sound  series  these  critical  points 
are  the  octaves  of  the  musical  scale. 

The  octave  corresponds  to  the  spectrum.  As  one 
may  say  that  the  ends  of  the  spectrum  are  more  similar 
than  the  middle  to  either  end,  so  double  the  vibration 
of  any  tone  gives  a  note  that  is  more  similar  to  it  in  one 
respect   than   the   intermediate    tones.     These   octaves 

^  Philosophische  Studien,  4,  511  ff. 

2  Zeitschr.  f.  Psychol,  u.  Phys.  d.  Sinnesorg.  16,  352  fif. 


154  FUNDAMENTALS   OF  PSYCHOLOGY 

constitute,  for  the  trained  ear  at  least,  regularly  recur- 
ring units  of  tone  within  which  again  the  notes  whose 
vibration  rates  form  a  ratio  of  2:3,  3:4,  4:5,  etc. 
with  the  lower  note  of  the  octave  constitute  other 
marked  resting  points  or  definite  qualities  which  may 
be  regarded  as  distinct  from  all  others.  Trained  ears 
are  more  likely  to  make  a  mistake  of  an  octave  in  the 
note  than  to  mistake  one  note  for  another  within  the 
octave.  This  may  possibly  be  due  to  musical  training, 
as  many  other  systems  of  music,  the  Chinese,  e.g.,  seem 
not  to  recognize  the  same  distinctions,  but  the  balance 
of  evidence  at  present  seems  to  favor  the  view  that  the 
distinction  is  fundamental. 

In  recent  discussions  much  has  been  made  of  this 
peculiar  quality  relation  of  qualities  of  the  notes  within 
the  octave.  It  has  been  suggested  by  Meyer,  Revesz, 
and  others  that  we  should  distinguish  two  ways  in  which 
tones  may  vary  from  each  other;  one  is  in  what  they 
call  quality  that  depends  upon  the  place  of  the  tone 
within  the  scale,  and  the  other  in  pitch  which  depends 
upon  the  absolute  vibration  rate.  We  shall  have 
occasion  to  notice  this  distinction  again. 

Tone-Color.  —  Two  other  differences  in  the  quality 
of  tones  may  be  mentioned.  One,  that  tones  of  the 
same  pitch  from  different  instruments  have  a  charac- 
teristic difference  ordinarily  spoken  of  as  timbre  or 
tone-color,  which  depends  upon  the  overtones  that 
are  added  to  the  fundamental.  Thus  in  the  C  of 
64  double  vibrations  from  a  piano  string  there  are  also 
found  the  c  of  128,  the  g  of  192,  the  c'  of  256,  the  e'  of 
320,  the  g'  of  384,  the  seventh  overtone  of  448  which 


SENSATION  —  AUDITION  I55 

does  not  correspond  exactly  with  any  note  in  the  scale, 
the  c''  of  512,  etc.  Every  multiple  of  the  rate  of  vibra- 
tion of  the  fundamental  is  represented,  theoretically, 
since  they  correspond  to  the  nodes  in  which  the  sound- 
ing body  vibrates,  and  these  nodes  are  formed  at  each 
small  fraction  of  the  length  of  the  sounding  body. 
The  first  ten  overtones  can  be  readily  heard  when 
intensified  by  resonators.  If  one  will  hold  down  a 
key  on  the  piano  that  corresponds  to  one  of  the  over- 
tones, one  can  hear  that  overtone  continue  to  vibrate 
after  the  fundamental  has  been  dampened  by  dropping 
the  key.  It  is  started  into  vibration  by  resonance  and 
continues  to  vibrate  for  a  time  after  its  excitant  has 
stopped.  With  practice  one  can  hear  the  overtones 
separately  with  the  unaided  ear.  Each  instrument 
has  its  own  arrangement  of  overtones,  and  these  give  it 
its  timbre.  The  tuning  fork  has  almost  none ;  in  the 
piano  they  are  present  in  fairly  even  strength,  while  in 
the  violin  certain  of  the  high  ones  are  emphasized  at 
the  expense  of  the  lower.  Each  of  the  musical  instru- 
ments owes  its  pecuKar  quality  to  the  number,  pitch,  and 
relative  strength  of  its  overtones. 

Tone  and  Noise.  —  The  other  even  more  fundamental  v 
difference  in  sounds  is  that  which  obtains  between  tones 
and  noise.  The  difference  is  sufficiently  familiar  to 
need  no  description.  Physically  as  well  as  psychologi- 
cally two  forms  of  noise  are  to  be  distinguished.  The 
more  usual  is  due  to  a  very  complex  mass  of  tones  that 
have  no  simple  relation  in  their  vibration  rates,  and 
have  even  been  said  to  be  non-pendular  in  character. 
Any  inharmonious  combination  of  many  tones  is  ac- 


156  FUNDAMENTALS   OF  PSYCHOLOGY 

cepted  as  noise.  A  noise  of  this  kind  passes  gradually 
over  into  tone,  as  the  degree  of  dissonance  is  lessened, 
or  the  tonal  element  comes  to  predominate.  If  there 
are  any  tones  that  are  not  reducible  to  the  ordinary 
pendular  or  sine  form,  they  may  also  be  present  in 
noise.  That  complex  sounds  like  the  sawing  of  wood 
or  the  rattle  on  a  city  street  are  merely  tones  in  great 
number  and  variety  without  any  harmonic  relation 
is  probable,  since  with  resonators  one  can  distinguish 
tonal  elements  in  them.  The  second  type  of  noise 
corresponds  to  a  simple  vibration  too  short  to  produce 
the  full  tonal  character.  If  one  will  cut  off  a  pure  tone 
after  only  one  or  two  full  \dbrations  have  been  made, 
one  obtains  a  sudden  noise  that  lacks  the  tonal  char- 
acter. This  is  usually  done  by  passing  the  tone  through 
a  tube  that  can  be  opened  to  permit  the  sound  to  pass 
for  only  a  fraction  of  a  second.  When  less  than  two  full 
vibrations  reach  the  ear,  the  effect  is  a  shock.  The  full 
tonal  character  of  the  sound  is  obtained  only  when 
sixteen  full  vibrations  are  heard.  Noise  and  tone,  then, 
are  different  only  in  the  time  of  stimulation  or  in  the 
arrangement  or  combination  of  the  elementary  waves, 
not  in  the  character  of  the  waves  themselves. 

Vowel  Qualities.  —  Much  controversy  has  resulted 
from  the  attempts  to  explain  the  characteristic  differ- 
ences of  the  vowels.  Helmholtz  and  Konig  beUeved 
that  they  were  due  to  the  presence  or  absence  of  over- 
tones. The  overtones  were  emphasized  by  the  reso- 
nance of  the  mouth  chamber  which  is  changed  in  shape 
by  the  contraction  of  certain  muscles.  This  supposi- 
tion was  confirmed  by  synthetizing  vowels,  —  i.e.  by  put- 


SENSATION  —  AUDITION  1 57 

ting  together  simple  tones  to  constitute  the  fundamental 
with  its  overtones.  Recently  there  has  been  revived 
by  Kohler  an  old  theory  of  Hermann  that  vowels  were 
not  always  due  to  the  presence  of  overtones  of  the 
fundamental  note  of  the  tone,  but  that  the  character- 
istic of  the  vowel  was  some  single  note  which  did  not 
change  with  the  pitch  of  the  fundamental,  as  would 
be  necessary  if  it  were  an  overtone.  These  charac- 
teristic notes  were  called  formants  by  Hermann  and 
were  assumed  to  be  developed  by  the  air  blown  through 
the  mouth  cavity,  which  was  given  a  different  form  for 
each  vowel.  Kohler  tested  a  number  of  individuals 
by  giving  them  a  series  of  tones  which  could  be  grad- 
ually changed  and  asked  them  to  say  when  the  tone  took 
on  a  vowel  or  consonant  character.  His  results  indi- 
cated that  the  vowels  were  about  an  octave  apart 
through  the  scale.  In  order  he  gives  the  following  tones 
as  corresponding  to  the  tone  of  letters :  m  =130, 
u  =  260,  0  =  520,  a  =  1040,  e  =  2080,  i  =  4100,  5  =  8200, 
/=  17,000,  c/z  =  34,000.  All  the  values  are  approxi- 
mate only  and  the  sounds  are  the  sounds  of  the  German 
letters.  Between  the  pure  vowels  are  mixed  ones. 
One  shades  gradually  over  into  the  other  and  both  ele- 
ments can  be  distinguished.  Not  only  does  this  theory 
serve  to  explain  the  vowel  sounds,  but  it  explains  the 
characteristic  differences  in  the  series  between  the 
octaves.  The  notes  repeat  themselves  in  the  octaves, 
and  the  beginning  of  the  repetition  is  marked  by  the 
change  from  one  vowel  tone  to  another.  It  is  suggested 
that  the  sensations  corresponding  to  increased  \dbra- 
tion  rate  may  be  pictured  as  a  spiral,  with  the  same 


158  FUNDAMENTALS   OF  PSYCHOLOGY 

notes  over  each  other.  How  far  the  results  of  Kohler's 
experiments  are  to  be  accepted  is  still  a  question, 
but  it  adds  one  more  to  the  puzzles  presented  to  a 
theory  of  tone. 

Certain  it  is  that  at  present  the  problem  of  the  attri- 
butes of  tone  is  in  a  very  confused  state.  All  agree 
that  pitch,  noise,  and  timbre  are  to  be  distinguished. 
But  to  these,  various  authorities,  Revesz,  Kohler,  and 
Meyer  among  them,  would  add  vocality  or  the  char- 
acteristic vowel  quality,  and  the  tonal  quality  that  is 
important  for  music  as  distinguishing  the  different 
qualities  within  the  octave.  The  musical  quality  is 
identified  with  the  vowel  quahty  by  Kohler,  since  the 
characteristic  vowel  tones  fall  upon  the  octaves.  Revesz, 
on  the  contrary,  would  make  pitch,  quality,  and  vocality 
distinct,  partly  on  the  basis  of  introspection,  partly 
because  he  has  found  pathological  cases  in  which  a 
patient  may  appreciate  one  and  not  the  other.  Pitch 
is  the  quahty  that  increases  regularly  with  rate  of  vibra- 
tion, musical  quality  undergoes  a  change  through  the 
octave  but  comes  back  to  the  identical  quaHty  an  octave 
higher,  while  the  vowel  quality  depends  upon  the  abso- 
lute pitch,  and  its  characteristic  points  of  change  are  at 
the  different  octaves.  How  far  these  distinctions  may 
prove  themselves  is  hardly  a  matter  even  for  speculation 
at  present. 

Tonal  Fusion.  —  Of  the  various  phenomena  that  were 
mentioned  in  connection  with  vision,  some  are  also  to 
be  noticed  in  sound.  The  phenomenon  of  mixture  of 
colors  is  replaced  by  fusion  of  tones.  The  two  are  not 
easily  comparable,  since  the  result  of  the  combination 


SENSATION  —  AUDITION  1 59 

of  tones  is  so  completely  dependent  upon  the  position 
of  the  notes  within  the  octave  and  is  so  complicated 
by  the  admixture  of  feelings.  In  the  first  place,  each 
note  in  a  fusion  can  with  a  Httle  practice  be  heard  sepa- 
rately, there  is  no  fusion  that  gives  an  intermediate  tone 
as  in  color,  and  no  cancellation,  no  phenomenon  allied 
to  complementariness.  In  the  second  place  there  is  a 
peculiar  added  quality,  the  degree  of  fusion  of  the  whole 
that  depends  upon  the  ratio  of  vibration  rates  of  the 
two  tones ;  the  smaller  the  numbers  that  represent  the 
ratios,  the  closer  the  fusion.  The  best  fusion  is  fur- 
nished by  the  octave,  whose  components  give  a  vibra- 
tion rate  of  1:2,  the  fifth,  2:3,  and  decreases  with  the 
ratios  represented  by  larger  numbers  as  the  second, 
8:9;  the  seventh,  8:15,  etc.  This  relation  holds  at 
least  approximately,  although  critics  have  insisted  that 
the  degree  of  fusion  in  certain  combinations  does  not 
correspond  accurately  to  the  smallness  of  the  numbers 
that  express  the  ratio  of  vibration  rates.  Thirdly, 
there  is  availability  of  the  combinations  for  musical 
effects,  depending  partly  upon  degree  of  fusion,  more 
upon  the  training  of  the  hearer.  This  dependence  upon 
training  is  shown  by  the  difference  in  what  is  regarded 
as  pleasant  between  occidental  and  oriental  music  and 
in  the  gradual  change  in  the  accepted  intervals  in  western 
music.  The  tritone,  the  fourth,  and  the  fifth,  the  ac- 
cepted intervals  of  the  Greeks,  have  gradually  given 
way  to  the  thirds  and  sixths,  and  now  we  see  seconds 
and  sevenths  admitted  to  music  under  certain  circum- 
stances. It  is  the  feeling  tone,  as  well  as  the  physical 
combinations,  that  determines  the  effect. 


l6o  FUNDAMENTALS    OF   PSYCHOLOGY 

Beats.  —  An  effect  of  combinations  that  is  purely 
sensational  is  found  in  the  beat.  If  two  tones  of  approx- 
imately the  same  pitch  are  sounded  together,  there  is 
heard  an  alternate  increase  and  decrease  of  the  tone 
which  comes  as  many  times  a  second  as  the  difference  in 
the  number  of  \dbrations  per  second  of  the  component 
tones.  Physically  this  is  due  to  the  fact  that  the  com- 
ponent tones  will  be  alternately  in  the  same  phase  and 
in  opposite  phases.  When  they  are  in  the  same  phase, 
the  resultant  wdll  be  the  sum,  when  in  opposite  phases, 
the  difference,  of  the  two  tendencies  to  vibrate.  When 
these  alternations  come  some  distance  apart,  they  are 
heard  as  distinct  swellings  and  diminutions ;  when  closer 
together,  merely  as  a  roughness  of  the  tone.  For  the 
theory  it  is  interesting  to  note  that  the  beats  seem  to  be 
carried  by  neither  of  the  tones  themselves,  but  by  a  tone 
intermediate  between  the  tones  that  produce  the  beats. 
This  we  must  come  back  to  later. 

After-sensations.  —  Like  colors,  tones  have  after- 
sensations,  but  only  positive  ones.  It  requires  some 
time  for  a  tone  to  reach  its  maximum,  and  also  it  persists 
some  little  time  after  the  physical  excitation  ceases. 
The  ear  is  much  more  rapid  in  its  adaptations  than  the 
eye,  however;  it  has  much  less  inertia.  According  to 
Mayer  separate  tones  can  be  heard  if  they  are  repeated 
as  frequently  as  27  per  second  for  notes  of  64  V  D  and 
204  times  per  second  for  a  note  of  1024.  There  are 
also  intermittent  after-sensations  of  tones,  but  they  are 
not  so  often  noticed  as  after-images.  Urbantschisch 
reports  that  single  primary  after-tones  may  last  from 
one  to  ten  seconds.     The  intermittent  after-images  may 


SENSATION  —  AUDITION  l6l 

follow  each  other  at  irregular  intervals  for  one  to  two 
minutes.  Each  after-sensation  will  last  from  lo  to  15 
seconds  at  intervals  of  from  10  to  20  seconds.  Usu- 
ally these  intermittent  tones  are  of  the  same  pitch  as 
the  objective  tone,  but  some  may  be  higher  or  lower. 
They  are  fainter  than  the  original  and  usually  fluc- 
tuate in  intensity. 

Corresponding  to  color  bKndness  are  rare  cases  of 
what  are  called  tone  islands,  —  the  patients  are  deaf 
to  Hmited  portions  of  the  scale  and  can  hear  notes 
above  and  below.  ^lore  frequent  are  indi\iduals  whose 
range  of  audition  is  shortened  above  and  below,  and  it 
is  a  fairly  general  rule  that  the  upper  notes  gradually 
cease  to  be  heard  with  increased  age. 

Combination  Tones.  —  An  interesting  phenomenon 
of  hearing  is  furnished  by  combination  tones.  When 
two  notes  are  sounded,  one  frequently  hears,  in  addition 
to  the  notes  themselves,  tones  that  correspond  to  the 
difference  between  their  vibration  rates  or  to  the  sum 
of  their  vibration  rates.  Thus  if  the  tones  c  and  e  of 
128  and  160  be  sounded  together,  one  wdll  hear  a  note 
corresponding  to  the  difference  in  their  \ibration  rates,  32. 
One  can  also  hear  a  second  difference  tone  whose  rate 
is  the  dift'erence  in  rate  between  the  higher  and  twice  the 
lower  (2 1  —  h)  of  96  and  a  third  tone  (3 1  —  2  h)  of  64. 
Some  authorities  report  that  they  hear  fourth  and  fifth 
difference  tones  named  on  the  analog}'  of  the  last.  The 
striking  aspect  of  these  tones  is  that  they  are  entirely 
subjective ;  they  cannot  be  heard  more  clearly  by 
means  of  resonators  than  by  the  unaided  ear,  and  all 
other  means  of  demonstrating  their  objective  existence 

M 


1 62  FUNDAMENTALS    OF   PSYCHOLOGY 

fail.     They  must  apparently  be  accounted  for  by  the 
physiological  or  psychological  theory  of  hearing.     An- 
other combination  tone  is  the  summation  tone.     This 
is  a  note  that  corresponds  to  the  sum  of  the  vibration 
rates  of  the  component  tones.     It  is  not  so  easy  to  hear 
as  the  difference  tones,  and  it  is  more  difficult  to  obtain   . 
pure  conditions  for  it,  as  in  many  cases  it  will  correspond   i 
to  an  overtone  or  to  a  difference  tone  between  the  over- 
tones.    The  summation   tones   are  probably  of  subjec-   j 
tive  origin,  but  no  satisfactory  explanation  has  been   ' 
given  of  how  they  originate. 

Theories  of  Hearing.  —  The  physiological  theory 
can  be  discussed  only  in  connection  with  the  structures 
about  the  endings  of  the  auditory  nerve  in  the  cochlea. 
As  was  said,  the  auditory  nerve  enters  the  centre  of 
the  modiolus  about  which  the  cochlear  canal  is  wound, 
and  the  sheet  of  fibres  extends  through  the  lamina 
spiralis  to  end  in  the  neighborhood  of  hair  cells  on  the 
basilar  membrane.  The  structures  here  are  somewhat 
complicated,  but  the  theories  have  made  no  use  of  most 
of  the  complications.  The  membrane  that  helps  to 
divide  the  cochlea  into  two  canals  consists  in  large  part 
of  transverse  fibres.  These  for  Helmholtz  constitute 
the  essential  part  of  the  basilar  membrane.  Below 
them  is  a  layer  of  connective  tissue  which  is  thicker 
than  the  layer  of  fibres.  On  the  basilar  membrane  are 
found  several  peculiar  structures.  The  most  striking 
of  these  are  the  rods  of  Corti.  These  consist  of  two 
rows  of  delicate  structures  curved  and  fitted  together 
at  the  top  to  form  a  clearly  defined  arch.  One  row 
leans  away  from  the  central  column,  the  other  towards 


SENSATION AUDITION 


163 


it,  and  the  two  seem  to  be  jointed  together  at  the  top. 
They  leave  an  opening  between  them,  the  canal  of  Corti. 
These  rods  are  not  continuous  longitudinally  and  are 
considerably  less  numerous  than  the  fibres  of  the  basilar 
membrane.  On  the  inner  side  of  the  arch  is  one  layer 
of  cells  with  a  tuft  of  hair  at  the  top ;  on  the  outer  side 
are  four  or  five  layers,  with  similar  tufts  that  extend 
through  a  membrane,  Kolliker's  membrane,  to  the 
lymph  of  the  cochlear  canal.  Covering  the  outer  por- 
tion of  the  basilar  membrane  are  relatively  thick  epi- 
thelial cells.  On  the  inner  side,  extending  out  from  and 
well  above  the  lamina  spiraHs  is  a  delicate  membrane, 
the  tectorial  membrane,  which  hangs  free  in  the  Kquid 
above  the  entire  \\idth  of  the  differentiated  mechanisms. 
These  can  all  be  made  out  in  Figure  55. 


s^ 


Fig.  55.  —  Organ  of  Corti.  h,  basilar  membrane ;  d,  outer  auditory  or  hair 
cells  ;  s,  inner  auditory  cell ;  /,  top  of  outer  rod  of  Corti,  forming  one  side  of  the 
arch  of  Corti ;  o,  inner  pillar  cell ;  g,  tectorial  membrane  ;  q,  nerve  fibres ;  n, 
nerve  fibres  extending  across  the  canal  of  Corti.     (From  Huber  after  Retzius.) 

On  first  sight  one  would  think  that  the  rods  of  Corti 
must  be  the  essential  organ  of  hearing.  They  are  so 
highly  developed  and  delicate  that  a  teleologist  would 
insist  that  they  must  have  some  specific  function. 


164  FUNDAMENTALS    OF   PSYCHOLOGY 

The  most  fully  developed  theory  is  that  of  Helmholtz. 
In  essentials  it  assumes  that  there  must  be  in  the  ear  |i 
resonators  tuned  to  each  tone  heard.     An  analogy  can  ^ 
be  drawn  with  the  piano  strings  which  vibrate  in  sym-  ; 
pathy  with  the  tones  that  are  present  in  the  outer  air.  | 
If  one  speaks  in  a  room  with  a  piano,  the  tones  of  the 
voice  will  be  heard  sounding  after  the  voice  has  ceased. 
If  one  will  hold  down  a  key  and  sing,  the  corresponding  j 
note  will  be  distinctly  heard  to  respond  in  sympathetic 
vibration.     Helmholtz  believed  that  there  must  be  res-  I 
onators  in  the  ear  which  respond  in  the  same  way  to  the  | 
vibration  for  which  they  are  tuned.     His  first  idea  was  i 
that  the  arches  of  Corti  must  be  these  organs.     When 
they  were  counted,  however,  it  was  found  that  there 
were  only   3000   of   them,    while   it   was   known   that 
some    11,000   tones  could   be   heard.     Helmholtz   then 
turned  for  his  resonators   to    the   fibres  of  the  basilar 
membrane.     These  are  sufficiently  numerous   (18,000- 
24,000)  to  provide  a  resonator  for  each  tone  that  can 
be  heard.     They  also  show  some  difference  in  length, 
—  at  the  upper  end  of    the    cochlea  they  are  approxi- 
mately 0.48  mm.  long,  at  the  lower  end  about  0.04. 
This  is  not  difference  enough  to  account  for  the  differ- 
ence in  pitch  that  they  are  supposed  to  show,  but  Helm- 
holtz assumed  that  they  were  differently  loaded  and 
tuned  by  that  means  for  the  different  tones. 

In  the  completed  theory,  then,  it  was  assumed  that 
there  were  in  the  basilar  membrane  fibres  which  were 
tuned  to  each  note  that  could  be  heard.  The  various 
complex  vibrations  were  impressed  upon  the  liquid  of 
the  inner  ear  by  the  oscillations  of  the  stirrup,  and  these 


SENSATION  —  AUDITION  165 

were  analyzed  into  their  parts  by  the  fibres.  In  a  piano 
tone,  or  other  note  rich  in  overtones,  a  separate  fibre 
was  set  into  vibration  by  the  fundamental  and  by  each 
of  the  overtones ;  in  a  chord  each  component  similarly 
aroused  a  different  fibre  or  group  of  fibres  and  each  was 
sent  to  the  centres  by  a  separate  nerve.  The  vibrations 
of  these  fibres  served  in  some  way  not  made  very  clear 
to  stimulate  the  nerve  fibres  between  the  hair  cells. 
The  \'ibration  of  the  fibres  was  dampened  by  the  tec- 
torial membrane,  which  was  assumed  to  drop  down  upon 
them  when  the  sound  ceased.  Noises  were  at  first 
assigned  to  the  vestibular  structures,  but  when  these 
were  discovered  to  have  another  function,  they  too  were 
regarded  as  due  to  excitations  of  many  fibres  in  the  basi- 
lar membrane.  Indirect  evidence  was  found  to  support 
the  theory  in  the  fact  that  in  cases  of  deafness  to  part 
of  the  scale,  parts  of  the  basilar  membrane  were  Kkely 
to  be  diseased.  Von  Bezold  has  found  that  patients 
who  have  the  so-called  tone  islands,  parts  of  the  scale 
that  they  cannot  hear,  also  are  found  after  death  to 
have  lesions  in  the  corresponding  part  of  the  basilar 
membrane.  In  the  aged  the  lower  part  of  the  basilar 
membrane  is  often  in  a  pathological  condition,  and  they 
fail  to  hear  high  tones. 

Criticism  of  Helmholtz's  Theory.  —  The  theory  is 
adapted  to  explain  a  number  of  the  facts  of  hearing. 
Beats  may  be  regarded  as  due  to  an  overlapping  of  the 
vibrating  portions  of  the  membrane,  and  thus  as  giving 
rise  to  an  interference  phenomenon  in  the  intermediate 
fibres.  On  this  assumption  each  tone  would  cause  a 
ribbon  of  several  fibres  to  vibrate  instead  of  a  single 


1 66  FUNDAMENTALS   OF   PSYCHOLOGY 

fibre  as  Helmholtz  first  asserted.  When  they  were  near 
together,  the  outer  edges  of  the  two  ribbons  would  have 
common  fibres.  These  would  tend  to  vibrate  with  the 
rates  of  both  notes,  and  the  interference  of  the  two 
movements  would  cause  the  beats.  This  view  receives 
support  from  the  fact  mentioned  earlier  that  it  is  a 
note  intermediate  between  the  other  two  that  beats 
rather  than  either  of  the  component  tones.  It  is  the 
intermediate  fibres  that  are  vibrating  at  two  different 
rates  and  consequently  carry  the  beats.  When  the 
vibrating  ribbons  are  sufficiently  far  apart  there  are  no 
interferences  and  so  no  beats. 

An  explanation  of  consonance  is  furnished  by  the 
Helmholtz  theory  on  the  basis  of  beats.  The  notes 
that  give  the  most  perfect  fusion  are  themselves  far 
enough  apart  not  to  beat  and  also  give  rise  to  no  beats 
between  their  overtones.  Thus  the  fifth  with  a  ratio  of 
vibrations  of  2 :  3  would  have  as  overtones  of  the  first 
components  4,  6,  8, 10,  etc.,  and  as  overtones  of  the  second 
component  6,  9,  12,  etc.  Of  the  first  four  overtones 
only  the  8  and  9,  9  and  10  would  be  near  enough  to  beat 
or  be  dissonant,  and  two  of  the  first  four  would  be  identi- 
cal, the  others  no  less  consonant  than  the  fundamentals 
themselves.  On  the  other  hand,  the  major  seventh,  with 
a  ratio  of  8 :  15,  while  giving  no  beats  between  the  funda- 
mentals, would  have  beats  between  most  of  the  overtones. 
The  fundamental  of  the  higher,  15,  would  beat  with 
the  first  overtone  of  the  second,  16,  the  third  overtone 
of  the  lower  beats  with  the  first  of  the  higher,  and  in 
general  there  are  many  beating  overtones  and  no  iden- 
tical ones  below  the  eighth  of  one  and  the  fifteenth  of 


SENSATION  —  AUDITION  167 

the  other.  In  general,  then,  dissonant  chords  may  have 
beats  either  between  the  fundamentals  or  the  overtones, 
while  consonant  chords  have  few  beats  if  any  between 
either  fundamentals  or  overtones.  This  mechanical 
theory  has  been  questioned,  as  will  be  seen  in  Chapter 
VIII. 

The  explanation  of  difference  tones  is  not  so  satis- 
factory. Helmholtz  at  first  thought  they  might  be 
beat  tones,  misled  by  the  fact  that  there  would  be  as 
many  beats  per  second  as  the  vibrations  per  second  of 
the  difference  tones.  This  was  given  up  when  it  was 
seen  that  the  beats  could  not  stimulate  the  correspond- 
ing fibre  in  the  basilar  membrane.  His  final  explana- 
tion was  that  they  must  be  produced  in  the  middle  ear. 
He  demonstrated  by  a  differential  equation  that  a  mem- 
brane loaded  on  one  side  alone  when  excited  simul- 
taneously by  two  rates  of  vibration  should  produce  a 
third  vibration  that  corresponds  in  its  rate  to  the  differ- 
ence between  the  rates  of  the  two  components,  but  he 
did  not  point  out  the  physical  correlates  of  his  mathe- 
matical values. 

On  the  whole  the  Helmholtz  theory  is  most  detailed 
of  any,  it  accounts  for  more  facts  than  the  others,  and 
receives  more  incidental  support.  Its  weakness  is  a 
conflict  with  the  anatomical  findings.  The  basilar 
membrane  does  not  consist  of  a  series  of  delicate  fibres 
hanging  relatively  free  and  separated  from  each  other. 
Instead,  the  fibres  are  embedded  in  a  mass  of  tissue  on 
both  sides  thicker  than  the  fibres  themselves.  Ayers 
tested  the  possibiHty  of  the  basilar  membrane's  vi- 
brating to  tones  on  the  ear  of  a  criminal  who  had  just 


1 68  FUNDAMENTALS   OF   PSYCHOLOGY 

been  executed,  and  found  that  even  with  this  perfectly 
fresh  material  and  the  most  favorable  conditions  no 
vibration  in  the  basilar  membrane  could  be  detected. 

A  recent  suggestion  of  Shambaugh^  would  remedy  the 
difficulties  that  arise  from  the  use  of  the  basilar  mem- 
brane as  the  vibrating  mechanism  and  at  the  same  time 
retain  the  theoretical  advantages  of  the  resonator 
theory.  This  consists  primarily  in  substituting  the 
tectorial  membrane  for  the  basilar  membrane  as  the 
resonating  organ.  According  to  Shambaugh,  the 
tectorial  membrane  is  a  very  delicate  sheet  of  fibres, 
attached  at  both  ends  and  penetrated  by  the  deHcate 
hairs  of  the  hair  cells.  He  also  asserted  that  in  his 
preparations  the  fibres  at  the  top  were  '  several  hundred 
times  as  long  as  those  at  the  bottom,'  affording  a  sulSi- 
cient  range  to  supply  resonators  for  the  different  pitches 
that  can  be  heard.  All  of  the  objections  to  the  Helm- 
holtz  theory  would  be  removed  and  all  of  its  advantages 
retained  if  these  statements  concerning  the  anatomical 
structures  should  be  confirmed. 

Unfortunately  for  the  theory,  Hardesty^  repeated  the 
observations  of  Shambaugh  on  the  same  kind  of  material, 
the  cochleae  of  young  pigs  and  pig  embryos,  and  is 
quite  as  fully  convinced  that  the  old  descriptions  of  the 
tectorial  membrane  are  in  the  main  correct.  It  is  at- 
tached at  but  one  end,  is  well  above  the  hairs,  and  comes 
into  contact  with  them  only  when  vibrating,  and  is 
only  about  three  times  as  wide  at  the  top  as  at  the  base 

1  Shambaugh,  Minute  Anatomy  of  the  Structures  of  the  Cochlea, 
Amer.  Journ.  of  Anatomy,  vol.  7,  p.  245. 

-Hardesty,  On  the  Nature  of  the  Tectorial  Membrane,  etc.,  Amer. 
Journ.  of  Anatomy,  vol.  8,  p.  109. 


SENSATION  —  AUDITION  1 69 

of  the  cochlea.  The  fact  that  it  is  attached  at  one  end 
only  would  prevent  it  from  \'ibrating  through  reso- 
nance; its  tissue  does  not  show  a  sufficiently  fibrous 
character,  and  the  width  is  not  sufficiently  different  to 
give  support  to  the  resonance  theory.  Who  is  right 
as  to  the  anatomical  structures,  new  work  must  deter- 
mine. 

Telephone  Theories.  —  Other  theories  all  abandon  the 
resonator  principle,  assuming  instead  that  some  struc- 
ture in  the  cochlea  must  vibrate  as  a  whole  and  the 
analysis  of  the  separate  tones  be  made  by  the  cortical 
centres.  Hensen  and  Rutherford  have  assumed  that 
the  basilar  membrane,  acting  much  like  the  plate  of 
a  telephone,  transmits  the  complex  notes  to  the  cortex 
where  analysis  takes  place.  Max  Meyer  has  a  somewhat 
similar  theory.  His  assumption  is  that  the  intensity  of 
the  tone  is  determined  by  the  distance  the  vibration 
extends  inward  from  the  oval  window,  while  the  quahty 
is  determined  by  the  rate  of  vibration  of  the  membrane 
as  a  whole.  Hardesty,  as  a  result  of  his  studies  men- 
tioned above,  has  abandoned  the  basilar  membrane  as 
the  vibrating  mechanism  and  assumes  with  Shambaugh 
that  the  tectorial  membrane  is  the  receiving  organ. 
Hardesty  assumes  that  the  vibrations  of  the  Hquid  are 
taken  up  by  the  tectorial  membrane  and  communi- 
cated to  the  hair  cells  and  thence  carried  to  the  brain, 
where,  as  in  the  other  theories  of  this  type,  analysis 
takes  place.  The  difficulty  with  this  whole  group  of 
theories  lies  in  the  assumption  that  differences  in  vibra- 
tion rate  so  sKght  as  one  in  ten  thousand  should  be 
appreciated   by    the    cortex,    while    the   most   delicate 


lyo  FUNDAMENTALS   OF  PSYCHOLOGY 

appreciation  of  differences  in  intensities  is  one  in  a 
hundred.  The  difference  in  intensity  that  can  be 
appreciated  by  the  ear  is  only  one  in  five.  On  tele- 
ological  grounds,  which  of  course  have  little  weight,  it 
seems  inexplicable  that  the  extension  of  the  auditory 
nerve  over  such  a  wide  area  with  relatively  complicated 
end  organs  should  have  no  particular  function. 

It  can  be  seen  that  in  spite  of  the  ingenuity  and  hard 
work  that  has  been  devoted  to  the  problem,  a  satis- 
factory theory  of  hearing  is  yet  to  be  developed.  The 
Helmhoitz  theory  has  the  advantage  of  all  the  others 
in  the  number  of  facts  that  it  explains  and  the  detailed 
nature  of  its  explanation  ;  it  suffers  from  the"  improbabil- 
ity of  its  demand  that  the  fibres  of  the  basilar  membrane 
vibrate  separately.  On  the  other  hand,  the  theories  that 
give  a  plausible  explanation  of  the  way  the  anatomical 
structures  may  act  make  large  demands  on  our  ability 
to  distinguish  differences  between  vibration  rates. 

REFERENCES 

Ladd-Woodworth  :  Elements  of  Phys.  Psych.,  pp.  196-208. 
Meyers  :  Experimental  Psychology,  chs.  iii-iv. 
Howell:  Physiology,  375-393. 

Helmholtz  :  Sensation  of  Tone.     Tr.  Ellis,  2d  edition. 
ScHAEFER :    Der  Gehorsinn,  Nagel's  Handbuch  der  Physiologic, 
vol.  iii,  pp.  476-588. 

Tactual  Sensations 

Cutaneous  Sensations.  —  The  sensations  from  the  skin 
are  simplest  of  all  and  their  organs. are  most  accessible, 
but  only  in  the  present  generation  have  the  more  im- 


SENSATION  —  TOUCH  17I 

portant  facts  concerning  them  been  discovered.  The 
same  distinctions  between  physical  stimulus,  physiological 
processes,  and  sensations  that  we  have  been  compelled  to 
make  in  the  other  senses  are  to  be  drawn  here.  The 
adequate  stimuH  for  the  skin  are  mechanical  and  thermal. 
But  while  the  stimuli  vary  only  in  intensity,  different 
sense  organs  are  affected  by  different  intensities,  and  cor- 
responding differences  in  sensation  result.  This  is  most 
marked  in  the  temperature  sense.  The  physicist  assures 
us  that  cold  is  nothing  positive,  but  merely  a  reduction  in 
the  amount  of  heat.  Nevertheless  when  the  temperature 
is  reduced  below  about  30°  C.  a  sense  organ  is  excited 
which  gives  rise  to  the  sensation  of  cold,  and  this  sensa- 
tion increases  as  the  temperature  is  lowered.  Above 
30°  there  is  a  similar  increase  in  the  stimulation  of 
the  organ  of  warmth  wdth  increasing  temperature. 
Similarly,  sHght  mechanical  stimuli  excite  sensations  of 
pressure  and  intense  ones  sensations  of  pain.  We 
then  have  four  distinct  sense  qualities,  while  there 
are  but  two  kinds  of  physical  stimulus.  More  clearly 
than  in  any  other  organ  can  the  sense  qualities  be  shown 
to  depend  upon  the  organ  stimulated. 

The  discovery  of  the  distribution  of  the  organs,  and  with 
that  the  settlement  of  most  of  the  problems  of  cutaneous 
sensibiHty,  is  a  matter  of  comparatively  recent  date.  It 
came  first  in  the  temperature  senses.  At  approximately 
the  same  time  and  altogether  independently  of  each 
other  three  investigators,  BHx,  a  Scandina\dan  (1882), 
Goldscheider,  a  German,  and  Donaldson,  an  American 
(both  1885),  found  that  the  skin  was  sensitive  to  tem- 
perature only  in  relatively  isolated  spots  rather  than 


172  fuxd,a:^iextals  of  psychology 

all  over,  as  had  been  earlier  supposed.  The  skin  was 
carefully  tested  point  by  point  with  a  cooled  or  heated 
metal  point,  and  it  was  found  that  at  certain  points 
irregularly  arranged  one  would  feel  cold,  at  others, 
warmth.  The  most  important  disagreement  in  the 
results  found  was  between  Goldscheider  on  the  one 
side  and  BHx,  vrith  practically  all  later  workers,  on  the 
other.  Goldscheider  discovered  warm  and  cold  points 
thickly  scattered  ever\-where  on  the  skin;  for  example, 
on  the  back  of  the  hand  there  were  68  cold  spots  and  56 
warm  spots  on  a  square  centimetre.  BKx  reported 
that  they  were  much  farther  apart,  and  all  later  investi- 
gators have  confirmed  his  results.  Sommer  counted 
carefully  the  number  in  many  square  centimetres  and 
found  that  there  were  from  6  to  24  cold  spots,  and  from 
o  to  3  warm  spots,  to  the  square  centimetre.  He  gave 
as  his  average  12  to  13  cold  and  i  to  2  warm  spots.  His 
estimate  for  the  whole  body  was  500,000  cold  and  30.000 
warm  spots. 

Indirect  Evidence  of  the  Existence  of  Warm  and  Cold 
Spots.  —  !Many  of  the  earlier  theories  assumed  that 
there  must  be  a  single  organ  for  warmth  and  cold. 
Hering,  for  example,  had  a  theor}'  which  would  make 
warm  and  cold  depend  upon  assimilation  and  dissimi- 
lation in  the  single  organ,  in  very  much  the  same  way 
that  his  complementar}^  colors  depended  upon  those 
processes  in  the  single  color  organ.  It  was  therefore 
essential  when  the  spots  were  first  mapped  to  prove  by 
other  e\idence  that  the  spots  were  distinct.  Certain 
characteristic  differences  in  the  way  the  two  organs 
respond  and  in  the  substances  that  stimulate  them  pro- 


SENSATION  —  TOUCH 


173 


\dded  this  e^'idence.  '  i.  It  takes  considerably  longer  to 
stimulate  the  warm  spots  than  the  cold  spots,  perhaps 
an  e\idence  that  the  former  are  farther  from  the  surface. 
2.  Certain  inadequate  stimuH  will  affect  one  but  not  the 


•.•• 


•       •  +  +  + 

f    +*  •  • 

+•  • 

•     •   •  + 

-•■•.•  +• 


•      +  + 

J. 


Fig.  56.  —  Map  of  temperature  spots  on  volar  surface  of  the  forearm.  The 
dots  represent  warm  spots  as  tested  at  a  temperature  of  41-48°  C. ;  the  crosses, 
cold  spots  tested  at  lo'^.     (From  Howell  after  von  Frey.) 

Other.  Cold  is  particularly  easy  to  excite  by  induction 
currents,  by  pressure,  or  even  by  heat.  Menthol  stim- 
ulates the  cold,  carbon  dioxide  the  warm  organs. 
3.  There  are  certain  larger  areas  of  the  body  in  which 
only  one  sort  of  sensation  will  be  found.  Thus  on  the 
cornea  and  conjunctiva  of   the  eye  cold  alone  is  felt, 


174 


FUNDAMENTALS    OF   PSYCHOLOGY 


warmth  is  lacking  altogether.     That  there  are  different 
organs  for  cold  and  for  warmth  is  not  now  disputed. 

The  Temperature  Scale.  —  The  more  detailed  rela- 
tion between  the  physical  temperature  and  the  sensations 
that  result  from  the  stimulation  may  be  given.     The 


\/ 


20 


Fig.  57-  —  Temperature  scale.  Shows  the  sense  organs  stimulated  and  the 
degree  of  stimulation  at  different  temperatures.  Figures  on  the  base  line  indi- 
cate the  temperature  in  centigrade,  the  height  the  degree  of  stimulation.  (After 
von  Frey.) 

critical  point  for  most  purposes  is  the  so-called  physi- 
ological zero  point  that  separates  cold  from  warm. 
This  point  varies  much  with  the  temperature  to  which 
the  skin  has  been  adapted.  For  a  covered  part  of  the 
body,  it  is  apparently  in  the  neighborhood  of  from  28°  to 
30°  C. ;    on  the  back  of  the  hand,  it  has  been  found  to 


SENSATION  —  TOUCH  1 7  5 

vary  between  23°  and  33°,  and  after  the  hand  has  been 
immersed  in  water  at  11°  for  some  time  water  at  12° 
seems  warm,  and  it  may  similarly  be  adapted  for  tem- 
peratures of  39°.  The  mdth  of  the  indifference  point 
seldom  is  greater  than  0.5°.  If  we  assume  an  indif- 
ference point  at  30°  C,  below  it  the  cold  spots  alone  are 
stimulated  to  somewhere  in  the  neighborhood  of  10°, 
where  pain  is  added  to  the  complex.  Above,  one  ob- 
tains warmth  alone  up  to  45°.  Here  the  cold  spots 
are  excited  in  addition  to  the  warmth,  and  the  combi- 
nation gives  hot  as  opposed  to  lukewarm.  This  excita- 
tion of  the  cold  organ  by  a  hot  stimulus  gives  what  is 
known  as  a  paradoxical  cold.  The  fact  was  first  dis- 
covered by  Alrutz  and  has  been  confirmed  by  von  Frey. 
One  experiment  performed  by  Alrutz  was  to  fatigue  the 
warm  spots  in  the  foot  by  keeping  it  immersed  for  some 
time  in  warm  water  and  then  to  swing  it  quickly  through 
hot  water.  The  hot  water  then  seemed  cold.  Above 
55°  to  60°  the  sensation  of  burning  heat  makes  its 
appearance  as  a  consequence  of  the  mixture  of  pain  with 
the  other  sensations.  The  question  naturally  arose 
as  to  whether  there  was  a  paradoxical  warmth  at  the 
lower  ranges  similar  to  the  paradoxical  cold.  The 
burning  sensation  after  long  exposure  to  cold  suggests 
that  the  warm  spots  might  be  stimulated.  Experiments 
by  Alrutz  and  Thunberg,  however,  gave  no  warrant  for 
the  assimiption.  The  warm  or  hot  sensations  at  low 
temperatures  are  probably  due  to  the  mixture  of  sen- 
sations of  pain  with  some  tingling  due  to  changes  in 
circulation.  Figure  58  shows  these  various  phenomena 
in  diagrammatic  form. 


176  FUNDAMENTALS    OF   PSYCHOLOGY 

Mechanical  Cutaneous  Sensations.  —  Very  much  the 
same  distinction  may  be  made  between  pressure  and 
pain  as  between  warm  and  cold.  Goldscheider  also 
discovered  that  only  certain  points  on  the  body  would 
respond  to  pressure.  There  was  approximately  the  same 
difference  of  opinion  between  Goldscheider  and  the 
others  as  to  the  number  of  spots.  Goldscheider  found 
many,  the  others  relatively  few.  Von  Frey,  who  has 
done  the  most  careful  and  most  recent  work  on  the 
pressure  sensation,  found  that  there  are  from  o  to  300 
per  square  centimetre.  On  the  whole  body  surface, 
excluding  the  head  where  they  are  the  most  numerous, 
he  estimates  there  are  approximately  500,000.  They 
are  more  numerous  than  either  kind  of  temperature 
spots.  In  determining  their  position  von  Frey  used 
fine  hairs  mounted  on  matches  or  similar  small  bits  of 
wood.  These  gave  a  very  small  point  and  a  constant 
pressure.  Wherever  there  were  hairs  on  the  body  he 
found  that  the  pressure  spots  corresponded  to  them. 
They  are  also  found  on  the  surfaces  free  from  hairs. 

Sensations  of  Pain.  —  Pain  has  been  even  more  in 
dispute  than  the  other  senses.  Until  von  Frey's^  work 
in  1896  it  had  usually  been  held,  either  that  pain  was  a 
feeling,  not  a  sensation  at  all,  or,  if  it  was  a  sensation, 
that  it  must  be  regarded  as  due  merely  to  the  over- 
stimulation of  the  pressure  organ.  Goldscheider  in  his 
investigations  modified  this  view  slightly.  Pain  was. 
indeed  carried  to  the  spinal  cord  by  the  same  neurones 
as  pressure,  but  there  took  a  different  course.  While 
the  pressure  sensation  continued  by  the  same  neurone 

^  Leipziger  Abhandlung,  1896. 


SENSATION  —  TOUCH  1 7  7 

up  the  posterior  columns,  the  intense  sensations  were 
supposed  to  force  a  way  across  a  synapse  to  new  neurones 
with  cells  in  the  central  gray  and  take  another  path. 
As  e\idence  that  there  is  this  more  difficult  path  through 
the  central  gray,  Goldscheider  adduces  the  slow  passage 
of  the  pain  sensation  to  the  cortex.  The  reaction  time 
for  pressure  is  from  0.12  to  0.2,  while  the  time  for  pain 
rises  to  0.6  to  0.8  second.  He  uses  this  theory  also 
to  explain  summation  pains  such  as  those  involved  in 
the  Chinese  water  torture,  in  which  drops  of  water  are 
permitted  to  fall  for  a  long  time  upon  the  same  point 
until  the  successive  slight  stimuH  give  rise  to  an  unbear- 
able pain.  The  summation  is  assumed  to  take  place 
in  the  cells  of  the  cord.  Also  the  effects  in  the  disease 
syringomyelia  are  mentioned  as  confirmatory  of  his 
theory.  In  this  disease  an  infection  extends  from  the 
central  canal,  destro}ing  the  cells  in  the  surrounding 
gray  matter.  Patients  suffering  from  this  disease  feel 
only  pressure  and  cold  in  certain  areas  of  the  skin,  but 
have  no  sensations  of  pain  and  warmth.  Goldscheider 
interpreted  this  to  mean  that  the  paths  for  pain  were 
destroyed,  while  the  paths  through  the  white  matter 
were  left  intact.  Goldscheider,  too,  explained  on  this 
theory  the  '  referred  pains '  so  prominent  in  most 
diseases.  He  assumes  that  two  or  more  regions  of  the 
body  are  connected  with  the  same  cells  in  the  cord. 
Thus  he  would  say  that  the  mucous  membrane  of  the 
stomach  and  the  skin  of  the  back  were  connected  with 
the  same  cells  in  the  cord.  When  certain  disturbances 
of  the  stomach  developed,  the  excitation  of  its  nerves 
would  be  carried  to  the  cells  in  the  cord  that  gave  rise 

N 


1 78  FUNDAMENTALS    OF   PSYCHOLOGY 

to  the  sensation  of  pain,  and  the  sensation  would  be 
carried  to  the  cortex.  But  since  the  same  cells  also 
transmit  pain  sensations  from  the  middle  of  the  back, 
and  we  are  much  more  familiar  with  those,  the  pain 
would  be  referred  to  the  known  region,  the  back,  rather 
than  to  the  unknown  region,  a  region  that  had  never 
been  seen  and  where  voluntary  contact  had  never  pro- 
duced pains.  A  somewhat  similar  theory  of  referred 
pains  has  been  given  by  Head  ^  without  accepting  the 
other  portions  of  Goldscheider's  theory. 

Pain  Spots.  —  More  recent  investigations  have  shown 
that  the  first  part  of  Goldscheider's  theory,  that  pain 
and  pressure  are  carried  to  the  cord  by  the  same  nerves, 
is  probably  incorrect.  Von  Frey,  in  particular,  by  very 
careful  mapping  of  the  skin  has  shown  that  there  are 
special  pain  spots  in  the  skin  in  addition  to  the  pres- 
sure and  temperature  spots.  The  mapping  was  on  an 
enlarged  scale  diagram  of  the  small  portion  of  the  skin 
worked  with.  The  skin  was  explored  with  a  sharpened 
horse  hair  under  a  magnifying  glass,  and  it  was  found 
that  sensations  of  pain  were  given  only  at  certain  points, 
mostly  in  the  small  Hues  of  depression  on  the  skin. 
These  were  found  to  be  much  less  sensitive  than  the  pres- 
sure spots,  required  about  one  thousand  times  as  great 
a  pressure  to  stimulate  them,  and  were  much  more 
numerous  than  any  other,  on  the  average,  one  hundred 
to  the  square  centimetre.  It  was  estimated  that  there 
are  between  two  and  four  million  pain  spots  on  the 
surface  of  the  body.  Much  corroboratory  evidence 
has  been  brought  to  confirm  the  results  of  mapping  the 

1  Brain,  1888. 


Fig.  58.  —  Termination  of 
sensory  ner\-e-fibres  in  the 
mucosa  and  epithelium  of 
the  cat.     (From  Huber.) 


179 


i8o 


FUNDAMENTALS   OF  PSYCHOLOGY 


.^hst 


Fig.  sg.  —  Nerve  endings  in  skin  and  about  hair  follicles,  c,  superficial  plexus 
of  fibres  in  skin  (free  nerve  endings  are  still  nearer  the  surface)  ;  //,  the  hair  with 
nerves  about  root.     (From  Barker,  after  Retzius.) 

spots.  It  has  been  found  that  there  are  some  parts  of 
the  body,  the  conjunctiva  of  the  eye,  e.g.,  where  there 
are  pain  spots  but  no  pressure  spots ;  others,  as  the  inner 


SENSATION 


TOUCH 


i8i 


lining  of  the  cheek,  where  there  are  pressure  spots  but 
no  pain  spots.  Another  bit  of  evidence  depends  upon 
the  slow  response  to  pain  men- 
tioned above.  If  a  pressure  spot 
be  stimulated  by  a  sHght  alter- 
nating electric  current  with  alter- 
nations of  fifty  or  sixty  per  second, 
the  separate  alternations  \\dll  be 
noticed.  If,  on  the  contrary,  the 
current  be  apphed  to  a  pain  spot, 
there  is  a  continuous  sharp  sen- 
sation. 

Cutaneous  Sense  Organs.  — 
The  sense  organs  for  these  differ- 
ent sensations  have  been  deter- 
mined with  var}ing  degrees  of 
certainty.  Pressure  spots  seem 
closely  connected  with  the  hairs  on  the  parts  of  the 
body  where  there  are  hairs.  The  spot  that  responds 
is  always  just  over  the  root  of  a  hair  (Fig.  59).  It  is 
probable  that  the  nerve  about  the  root  is  stimulated  by 
the  hair  which  acts  as  a  lever  as  it  is  bent.  On  the 
surfaces  without  hairs,  palms  and  soles  of  the  feet, 
von  Frey  suggests  that  the  Meissner  corpuscle  (Fig.  60) 
is  the  organ.  Pain  spots  are  ascribed  to  the  free  nerve 
endings  (Fig.  58).  These  come  closest  to  the  surface 
of  any  of  the  end  organs  in  the  skin  and  the  sensations 
of  pain  are  aroused  by  the  most  superficial  stimulations. 
Acids  that  affect  only  the  epidermis  give  pain  sensa- 
tions \^dthout  sensations  of  pressure  or  temperature.  It 
is  more  difficult  to  determine  the  organs  for  tempera- 


FiG.  60.  —  Tactile  cor- 
puscle of  Meissner  from  the 
skin  of  the  toe.  N,  nerve 
fibre.     (From  Barker.) 


l82  FUNDAMENTALS    OF   PSYCHOLOGY 

ture  and  the  results  are  less  trustworthy.  Following  von 
Frey  again,  we  may  regard  the  end  organs  of  Krause 
(Fig.  6i)  as  the  sense  organs  of  cold,  since  they  with 
the  free  nerve  endings  are  the  only  sense  organs  found  in 
the  conjunctiva,  where  also  only  pain  and  cold  can  be 
felt.  Because  the  sensations  of  warmth  seem  to  origi- 
nate well  below  the  surface  and  the  organ  of  Rufhni 
also  is  found  relatively  deep,  that  has  been  regarded  as 
the  sense  organ  of  warmth  (Fig.  62). 

Regeneration  of  Cutaneous  Sensations.  —  An  experi- 
ment performed  by  Head  and  Rivers  tends  to  estabhsh 

a  second  classifica- 
tion of  cutaneous 
sensations  that  has 
not  been  brought 
into  complete 
agreement  with 
the    one    given 

Fig.  61.  — End  bulb  of  Krause.     (From  Barker.)      ^t)OVe.       ihcy    CUt 

the  ulnar  nerve 
where  it  is  near  the  surface  at  the  elbow  and  then  studied 
the  sensations  that  remained  and  the  gradual  reappearance 
of  sensations  as  the  nerve  regenerated.  At  once,  after 
the  nerve  was  cut,  all  sensations  from  the  skin  proper 
disappeared.  Neither  pressure  nor  pain,  wannth  nor 
cold,  could  be  felt.  When  more  intense  stimulation 
was  applied,  pressure  and  pain  could  be  felt  from  the 
tissues  under  the  skin,  of  approximately  the  same  qual- 
ity as  from  the  normal  deeper  tissue  in  the  arm.  This 
they  call  the  deeper  lying  sensibility.  After  the  lapse 
of  forty-three  days,  sensations  first  began  to  return  to 


SENSATION  —  TOUCH 


183 


the  skin.  The  first  evidence 
of  regaining  sensation  was  in 
the  diminution  of  the  area 
insensitive  to  pain.  On  the 
one  hundred  twelfth  day  sen- 
sations of  cold  made  their 
appearance,  and  the  area  sen- 
sitive to  pain  had  much  in- 
creased. Nearly  two  months 
later  the  hairs  were  found  to 
be  sensitive  to  light  touch  and 
a  few  warm  spots  made  their 
appearance.  One  hundred 
and  ninety  days  after  the 
operation  all  of  the  sense 
qualities  had  returned  over 
approximately  the  entire  area. 
But  each  of  the  sensations  was 
limited  in  some  way  as  com- 
pared with  the  normal.  Tem- 
peratures below  37°  C.  and 
above  27°  C.  could  not  be  felt 
at  all.  Pain  sensations  could 
be  felt  only  from  unusually 
intense  excitations,  and  then 
were  exceedingly  disagreeable 
and  diffuse,  and  were  gener- 
ally referred  to  some  point 
at  a   distance  from  the    one 

stimulated.     Touch  could  be  felt  only  on  the  hairs,  — 
when  an  area  was  shaved,  no  touch  was  felt.     The  sen- 


FlG.    62. 


—  End   organ  of  Ruffini. 
(From  Barker.; 


184  FUNDAMENTALS    OF   PSYCHOLOGY 

sibility  producing  this  condition  the  investigators  call 
protopathic. 

Curiously  enough  there  was  discovered  one  small 
triangle  in  the  affected  region  in  which  all  the  quahties 
were  present  that  were  lacking  from  the  rest.  Tem- 
peratures between  27°  and  37°  C.  could  be  noticed  but 
none  of  the  extremes.  No  pain  was  felt;  pricks  gave 
mere  sensations  of  contact  and  were  always  correctly 
localized.  Perhaps  most  remarkable  of  all,  light  con- 
tact with  cotton  wool  was  appreciated  on  this  small 
triangle  from  the  beginning  and  was  correctly  localized 
whether  hairs  were  or  were  not  stimulated.  This  more 
highly  developed  and  more  accurate  sensibility  was 
known  as  the  epicritic.  After  the  lapse  of  a  year, 
the  epicritic  sense  returned  to  the  entire  area.  The 
protopathic  sensibility  had  reappeared  in  the  small 
triangle  with  epicritic  sensitivity  only,  one  hundred 
ninety-eight  days  after  the  operation.  This  experi- 
ment indicates  that  three  sets  of  sensory  nerves  supply 
any  member.  One  is  found  in  the  deep  tissues,  the  two 
others  in  the  skin.  Of  the  latter  one  provides  the  coarser, 
more  intense  sensations,  the  other  the  more  delicate. 
The  protopathic  is  stimulated  only  by  relatively  intense 
pressure  and  that  only  on  the  hairs  ;  very  intense  stimuli 
also  give  pain.  It  also  is  affected  by  the  extremes  of 
temperature  alone.  The  epicritic  sense,  on  the  other 
hand,  supplies  the  gaps  left  by  this  sense ;  it  appreciates 
moderate  temperatures  and  slight  pressures.  The  rela- 
tion between  the  separate  spots  that  have  been  shown 
to  produce  the  specific  sensations  and  the  epicritic 
and  protopathic  sensibilities  has  not  been  completely 


\ 


SENSATION  —  TASTE  1 85 

worked  out.  It  seems  difficult  at  first  sight  to  harmon- 
ize the  two  sets  of  results,  and  another  series  of  obser- 
vations on  a  subject  with  a  regenerating  nerve  which 
shall  include  mapping  of  the  spots  at  different  stages  is 
desirable  to  complete  our  knowledge,  and  to  determine 
how  far  the  two  can  be  made  to  agree. ^ 

Sensations  of  Taste 

Gustatory  Sensations. — While  tactual  sensations  have 
been  found  much  more  numerous  than  was  thought,  as 
knowledge  about  them  increases  sensations  of  taste 
have  been  diminished  in  number  quite  as  definitely  and 
markedly.  The  popular  mind  to-day  and  the  scientific 
opinion  of  one  hundred  years  ago  assumes  that  there 
are  a  very  large  number  of  taste  qualities.  Even  after 
experiments  had  been  made,  it  was  generally  believed 
that  at  least  six  could  be  distinguished.  The  older  list 
included  nauseating  tastes,  aromatic,  and  other  qualities 
that  we  now  know  to  be  derived  from  smell.  Chevreul 
showed  in  1824  that  these  must  be  smell  qualities  by  his 
discovery  that  they  disappeared  upon  closing  the  nos- 
trils. Until  relatively  recently  salt,  sweet,  sour,  bitter, 
metallic,  and  alkaline  were  regarded  as  the  primary 
tastes.  The  metallic  seems  on  closer  experimentation 
to  be  a  compound  of  taste  with  smell  and  wdth  mechan- 
ical and  perhaps  muscular  sensations.  The  metallic 
surface  may  produce  slight  muscular  contractions  in 
the  neighborhood  of  contact  which  add  to  the  other 
taste  and  smell  sensations  to  produce  a  complex.     Alka- 

^  Rivers  and  Head,  A  Human  Experiment  in  Nerve  Division,  Brain, 
xxxi,  323. 


i86 


FUNDAMENTALS   OF  PSYCHOLOGY 


lies  if  strong  may  make  the  tongue  slippery  and  may 
also  produce  puckering  of  the  surface  of  the  tongue. 
Von  Frey  has  shown  by  closing  the  nostrils  while  tasting 
that  alkalies  also  contain  odors.  When  the  tongue  is 
at  rest  and  the  nose  closed,  the  only  sensation  is  a  slight 
bitter.     Eliminating  all  sensations  of  smell,  which  fur- 


Fig.  63.  —  Fu 


ingiform  papilla  fruiu  liuuuui  lun^ui 


nish  a  large  part  of  what  is  called  taste  in  gastronomic 
relations,  and  all  tactual  and  temperature  sensations, 
such  as  the  biting  of  spices,  etc.,  wc  have  left  only  four 
true  tastes,  —  sweet,  salt,  sour,  and  bitter. 

Sense  Organs  of  Taste.  —  The  problem  of  the  organ 
of  taste,  and  its  specific  type  of  reaction,  is  similar  to  the 
same  problem  on  the  skin,  but  slightly  more  compli- 
cated.    The  sense  endings  of  taste  arc  found  primarily 


SENSATION  —  TASTE 


187 


upon  the  tongue,  but  also  in  some  numbers  upon  the 
soft  palate,  upon  the  cords  of  the  larynx,  the  epiglottis, 
and  in  children  also  on  the  inner  lining  of  the  cheek  and 
even  on  the  walls  of  the  middle  ear.  On  the  tongue  the 
organs  are  found  primarily  in    the  papillae.     These  are 


Suhijetnmul    cell 


InUrgemmal   fibrils 

Fig.  64.  —  Taste  buds  and  endings  of  gustatory  nerve ;  c  shows  taste  cells 
about  a  central  supporting  cell ;  h,  fibrils  around  and  between  the  taste-buds. 
(From  Barker.) 

depressions  of  various  shapes  and  sizes.  The  most 
striking  are  the  circumvallate  papillae,  from  seven  to 
twelve  circular  depressions,  much  like  the  moat  of  a 
walled  town,  arranged  in  an  angle  upon  the  back  of  the 
tongue.     The  most  numerous  t>pe  in  man  are  the  fungi- 


1 88  FUNDAMENTALS    OF   PSYCHOLOGY 

form,  whose  small  red  openings  may  be  seen  upon  the 
tip  of  the  tongue.  In  some  humans  the  foliate  papillae 
are  present  and  have  sense  organs.  They  are  very 
prominent  in  animals.  The  real  sense  ending  is  the  taste 
bud  or  beaker.  These  are  collections  of  taste  cells  and 
supporting  cells  arranged  in  the  form  of  a  bud.  The 
taste  cells  have  hairs  on  their  ends  that  extend  into  the 
papillae  where  they  come  into  contact  with  the  saliva 
in  which  the  chemical  substance  that  gives  rise  to  the 
taste  has  been  dissolved.  Around  the  taste  cells  are 
nerve  fibrils  bare  of  their  medullary  sheaths.  The 
function  of  the  papillae  is  apparently  to  catch  the  saliva 
and  permit  it  to  come  into  contact  with  the  taste  cells, 
and  there  to  start  the  nervous  impulse. 

Doctrine  of  Specific  Energies  for  Taste.  —  Much  dis- 
cussion has  been  devoted  to  the  question  whether  a 
single  taste  bud  in  the  papillae  can  give  rise  to  one  only 
or  to  more  than  one  sensation.  Experiments  performed 
by  Oehrwall  of  stimulating  the  papillae  separately  showed 
that  more  than  one  sensation  might  be  received  through 
a  single  papilla.  He  mapped  accurately  125  papillae 
and  then  stimulated  each  separately  with  solutions  of 
sugar,  quinine,  and  tartaric  acid.  Of  these,  27  gave  no 
response  at  all,  60  responded  to  all  three  substances, 
12  gave  acid  only,  3  sweet  only,  none  bitter  only,  4 
gave  sweet  and  bitter,  12  sweet  and  acid,  7  acid  and 
bitter.  From  this  experiment,  which  has  been  re- 
peated by  several  investigators  with  approximately 
the  same  result,  it  is  evident  that  the  papillae  cannot 
be  regarded  as  the  organs  of  different  special  sense 
qualities  as  are  the  spots  on  the  skin.     It  is  suggested 


I 


SENSATION TASTE  1 8^ 

by  the  supporters  of  the  doctrine  of  specific  energies 
that  the  immediate  sense  end  is  the  taste  bud  and  that, 
as  there  are  always  many  of  these  in  each  papilla,  it  is 
possible  that  each  taste  corresponds  to  a  particular  sort 
of  nerve  end,  but  that  several  different  kinds  are  found 
in  each  papilla.  As  the  separate  beakers  cannot  be 
stimulated  individually,  this  assumption  cannot  be 
confirmed  directly.  Some  indirect  e\'idence  in  its 
favor  is  offered  by  the  fact  that  on  the  application  of 
certain  drugs  the  tastes  disappear  one  at  a  time,  pre- 
sumably due  to  the  fact  that  the  primary  end  organs 
are  aff'ected  with  different  ease.  Thus,  cocaine  applied 
to  the  tongue  destroys  first  the  sensation  of  bitter,  and 
the  others  in  succession,  while  g}Tnnemic  acid  first 
destroys  the  sensation  sweet.  Similarly,  the  distribu- 
tion of  the  taste  sensitivity  on  the  tongue  tends  to  con- 
firm the  same  theory.  Bitter  is  most  prominent  on 
the  back  of  the  tongue,  —  in  some  individuals  is  con- 
fined to  that  region ;  sweet  is  more  pronounced  on  the 
tip,  sour  on  the  sides,  while  salt  is  more  generally  dis- 
tributed. The  distribution  varies  from  individual  to 
individual.  In  some,  bitter  will  be  lacking  altogether 
on  the  tip,  while  in  others  it  is  present,  but  in  few 
papillae.  A  similar  statement  may  be  made  for  each  of 
the  taste  qualities.  As  further  evidence  that  there  are 
specific  endings  for  each  quality,  the  same  substance  will 
produce  a  different  taste  as  it  is  applied  to  one  part  of 
the  tongue  or  the  other :  sodium  sulphate  has  a  sweet 
taste  on  the  tip,  a  bitter  taste  on  the  back  of  the  tongue, 
a  difference  that  must  be  due  to  the  organ  stimulated. 
Similarly,  pressure  or  electrical  stimulation  of  the  chorda 


IQO  FUNDAMENTALS    OF   PSYCHOLOGY 

tympani,  one  of  the  nerves  of  taste,  where  it  passes 
through  the  middle  ear  may  produce  sensations  of  taste. 
Still  another  bit  of  evidence  for  the  independence  of 
the  organs  for  the  different  tastes  is  difference  in  the 
time  required  for  stimulation.  On  the  tip  of  the  tongue 
salt  requires  from  0.25-0.72  second  to  be  appreciated, 
sweet,  0.30-0.85,  sour,  0.64-.070,  bitter,  1-2  seconds. 
The  longer  time  for  bitter  is  especially  striking.  While 
the  doctrine  of  specific  energies  is  not  open  to  direct 
test,  the  indirect  evidence,  so  far  as  it  exists,  supports 
the  hypothesis. 

Attempts  have  been  made  to  discover  some  relation 
between  the  chemical  composition  of  substances  and 
their  tastes.  As  is  well  known,  acids  are  sour  so  gen- 
erally that  the  two  words  are  popularly  synonymous 
as  applied  to  taste,  and  in  German  are  designated  by 
the  same  word.  There  are,  however,  many  exceptions 
on  both  sides.  For  the  other  qualities  the  lack  of  rela- 
tion between  the  chemical  composition  and  taste  is 
striking.  The  more  familiar  sweets  are  carbohydrates, 
but  lead  acetate,  salts  of  the  other  heavy  metals,  and 
even  some  alkalies  have  sweet  as  one  of  the  component 
tastes.  Much  the  same  statement  may  be  made  of  the 
bitter  substances.  Usually  they  have  a  complex  mole- 
cule, and  the  more  complex,  the  more  bitter,  but  no  more 
accurate  law  has  been  developed.  The  simple  salts 
are  usually  more  or  less  salt,  but  there  are  many  excep- 
tions. In  general,  the  attempts  to  correlate  taste  and 
chemical  composition  have  led  to  no  noteworthy  results. 

Taste  Fusions  and  Taste  Contrasts.  —  The  taste 
qualities  show  some  of  tlie  interrelations  found  in  vision, 


SENSATION  —  TASTE  19I 

Tastes  mix  with  each  other,  with  the  cutaneous  sensi- 
tivities, and  with  odors  to  produce  complexes  that  are 
not  readily  analyzable.  The  statements  hold  less  for 
taste  alone  than  for  mixtures  with  the  cutaneous  and 
olfactory  senses.  It  seems  that  sweet  and  sour,  sweet 
and  bitter,  combine  in  foods  to  advantage.  Salt  and 
sweet  have  approximately  the  relation  of  complementary 
colors.  When  mixed  in  weak  solutions,  KJesow  found 
that  they  nullify  each  other.  Also  when  applied  to 
neighboring  areas  of  the  tongue,  they  reenforce  each 
other,  i.e.  show  contrast  effects.  Thus  if  one  pour  upon 
one  side  of  the  tongue  a  solution  of  sugar  too  weak  to 
be  tasted,  and  upon  the  other  a  salt  solution,  the  sugar 
will  be  tasted.  Even  distilled  water  will  by  the  same 
means  be  given  a  sweet  taste.  Other  tastes,  as  sweet 
and  bitter,  applied  to  opposite  sides  of  the  tongue,  when 
intense,  may  alternate,  first  one  appears,  then  the  other, 
a  process  resembling  binocular  rivalry  of  colors. 

The  nerves  of  taste  offer  some  complication.  Ac- 
cording to  Zander,  there  are  three  nerves  of  taste  and 
one  of  cutaneous  sensibility.  Of  the  true  taste  nerves, 
the  glosso-pharyngeal,  the  ninth,  suppHes  the  back 
portion  of  the  tongue ;  the  vagus  supplies  the  taste 
buds  of  the  larynx  and  epiglottis  and  a  small  area  on 
the  very  back  of  the  tongue ;  while  the  chorda  tympani 
carries  the  sensations  from  the  forward  areas.  The 
chorda  tympani  enters  the  tongue  as  a  part  of  the  lin- 
guahs,  the  other  portion  of  which  is  a  branch  of  the  tri- 
geminus, and  is  the  nerve  of  cutaneous  sensibility.  In  its 
midcourse  it  is  alone,  and  then  enters  the  brain  stem  as 
part  of  the  intermediate  nerve. 


192 


FUNDAMENTALS   OF  PSYCHOLOGY 


Olfactory  Sensations.  —  The  organ  for  smell  is  sit- 
uated in  a  narrow  cleft  at  the  very  top  of  the  nasal 
cavity,  just  under  the  olfactory  lobe  at  the  base  of  the 
brain.  The  olfactory  area  is  marked  by  a  brown  pig- 
ment which  extends  over  the  upper  portion  of  the  sep- 


FiG.  65.  —  Olfactory  apparatus.  D,  the  olfactory  membrane  and  endings; 
B,  glomeruli  where  end-brush  of  olfactory  neurones  connects  with  dendrite  of  the 
more  central  neurones.     (From  Barker  after  Ramon  y  Cajal.) 


tum  and  the  roof  of  the  olfactory  fissure.  The  olfactory 
area  is  much  smaller  in  man  than  in  animals  that  make 
more  use  of  the  olfactory  sense,  and  much  smaller  in 
man  than  was  earlier  supposed,  since  the  brown  pigment, 
which  was  at  first  assumed  to  mark  it,  is  more  widely 
distributed    than    the    olfactory    sense    endings.     The 


SENSATION  —  SMELL  1 93 

olfactory  fissure  is  above  the  direct  respiratory  path 
—  only  eddies  of  the  air  inspired  or  expired  reach  it. 
This  is  a  protective  measure,  as  dust  and  other  harmful 
impurities  are  largely  prevented  from  affecting  the  end- 
ings. The  end  organ  proper  is  found  in  the  olfactory 
cells,  true  nerve  cells,  which  here  alone  reach  the  outer 
surface  of  the  body.  These  cells  end  in  hairs  that 
project  slightly  from  the  surface.  The  axone  of  the 
cells  passes  upwards  through  numerous  openings  in  the 
skull  to  make  connections  in  the  glomeruli  with  neurones 
of  the  olfactory  lobe,  and  thence  to  connect  with  the 
cortical  areas  for  smell.  Between  the  olfactory  cells  are 
supporting  cells.  The  chemical  substance  that  gives 
rise  to  the  odor  is  carried  in  the  inspired  or  expired  air 
and  comes  into  direct  contact  with  the  hairs  of  the 
olfactory  cells,  where  we  may  assume  that  the  chemical 
reaction  excites  the  nervous  impulse. 

Olfactory  Qualities.  —  How  many  sensations  of  smell 
there  are  is  still  a  moot  question.  The  organ  is  so  sit- 
uated that  no  direct  experiment  may  be  made  upon  it, 
and  the  indirect  experiments  either  have  not  been 
carried  far  enough  or  are  inaccurate.  Aronsohn  long  ago 
attempted  to  determine  the  number  by  a  fatigue  method. 
His  theory  assumed  that  one  might  tire  the  organ 
by  smelling  some  one  substance,  rosewater,  e.g.,  until 
that  substance  could  no  longer  be  detected,  and  then 
while  the  fatigue  persisted,  test  the  odors  of  different 
substances.  Any  that  could  still  be  detected  would 
belong  to  some  other  class,  must  be  sensed  through  some 
other  organ ;  those  that  could  not  be  distinguished  would 
belong  to  the  same  class.     The  method  has  been  proved 


194        •  FUNDAMENTALS   OF   PSYCHOLOGY 

to  be  practical,  but  the  large  number  of  substances  to 
be  tested  and  the  difficulty  in  knowing  whether  the 
organ  is  still  fatigued  for  the  standard  odor  have  pre- 
vented its  extensive  application.  Other  evidence  of 
the  existence  of  separate  olfactory  organs  is  furnished 
by  pathology.  In  certain  diseases  of  the  olfactory 
region,  the  odor  of  certain  substances  will  be  lost  while 
others  will  be  retained.  But  the  observations  have  not 
been  carried  far  enough  to  give  an  accurate  classification. 
Zwaardemaaker,  who  has  done  most  work  on  the 
subject,  has  suggested  the  following  nine  groups  of  odors  : 

1.  iEthereal.  Certain  fruit  odors,  ether,  the  esters, 
etc. 

2.  Aromatic.     Spices,  resin,  camphor,  etc. 

3.  Fragrant.  Odors  of  certain  flowers  and  perfumes, 
balsam. 

4.  Ambrosiac.     Amber  and  musk. 

5.  Alliaceous.  Onions,  garlic,  rubber,  chlorine,  sul- 
phur, etc. 

6.  Empyreumatic.     Smoke,  benzol,  phenol,  etc. 

7.  Hircine.  Goat  odors,  caproic  acid,  perspiration, 
etc. 

8.  Repulsive  odors.     Opium,  acanthus,  etc. 

9.  Nauseating.  Decaying  flesh,  substances  that  ex- 
cite incipient  vomiting  reflexes. 

While  this  classification  is  the  best  that  we  have, 
many  obvious  objections  may  be  made  to  it.  Nagel 
has  found  that  in  several  instances  substances  belong- 
ing to  the  same  class  will  be  shown  by  the  fatigue  test 
to  be  excited  in  different  organs.  Evidently,  too, 
several   of   the   groups   are   characterized    by   qualities 


SENSATION 


SMELL 


195 


^ 


altogether  foreign  to  odors.  Thus  the  offensive  odors 
owe  their  name  and  common  quality  to  the  unpleasant 
feeling  they  arouse ;  the  empyreumatic  to  the  pain 
quality,  a  cutaneous  sensation  derived  through  the  fifth 
nerve,  not  through  the  sense  of  smell ;  and  the  nauseat- 
ing to  sHght  movements  in  the  oesophagus.  While 
each  of  these  processes,  together  with  taste,  mixes  with 
odors  to  produce  a  percept  that  is  not  immediately 
analyzable,  they  do  not  constitute  true  odors.  All  that 
can  be  said,  then,  is  that 
there  is  a  large  number  of 
odors,  how  many  we  do 
not  know,  each  of  which 
probably  has  its  own  sense 
organ.  These  quah  ties  mix 
with  the  cutaneous  sensa- 
tions from  the  mucous 
membranes  of  the  nose, 
— one  quality  of  smoke, 
e.g.,  is  the  same  from  the 
eyes  as  from  the  nose,  —  and  with  tastes.  We  usu- 
ally do  not  distinguish  the  different  components :  if 
the  complex  comes  from  food  in  the  mouth,  we  call  the 
whole  a  taste ;  if  from  the  air  outside,  we  call  the  whole 
an  odor. 

Attempts  have  been  made  to  connect  the  qualities  of 
smell  with  the  chemical  composition  of  substances.  In 
general  it  may  be  said  that  most  odorous  substances 
are  found  in  the  fifth,  sixth,  and  seventh  groups  in  the 
system  of  Mendelejeff.  Haycraft  has  also  shown  that 
in  many  cases  the  intensity  of  the  smell  in  a  group 


Fig.  66.  —  Zwaardemaaker's  olfactom- 
eter.    (From  Titchener.) 


196  FUNDAMENTALS    OF   PSYCHOLOGY 

increases  fairly  regularly  with  the  complexity  of  the  mole- 
cule. There  are  exceptions  to  these  rules  and  no  com- 
plete formulation  may  be  made  of  them.  It  is  probable 
that  the  chemical  substance  is  borne  on  the  inhaled 
and  in  less  degree  by  the  exhaled  air  to  the  olfactory 
nerves  and  there  by  direct  chemical  action  arouses  the 
nervous  excitation. 

Mixtures  and  Compensations  of  Odors.  —  Mixtures 
and  compensations  of  smells  can  be  easily  demonstrated. 
For  these,  as  for  making  all  quantitative  tests  of  odors, 
Zwaardemaaker  made  use  of  an  instrument  he  called 
the  olfactometer.  In  essentials  it  consists  of  one  tube 
with  a  curved  end  to  be  inserted  in  the  nostrils,  and  of 
a  second  tube  of  larger  size  containing  an  inner  lining 
of  the  substance  to  be  investigated  to  be  slipped  over 
the  former.  The  amount  of  stimulation  is  measured 
by  the  area  of  the  outer  tube  exposed  beyond  the  inner. 
If  they  are  even,  the  air  entering  the  inner  tube  absorbs 
none  of  the  substance  on  the  outer ;  and  the  more  the 
outer  projects  beyond  the  inner,  the  more  saturated 
with  particles  is  the  air  that  enters  the  nostril.  In  the 
double  olfactometer  of  this  sort  a  tube  is  appHed  to  each 
nostril.  It  is  found  that  if  certain  substances,  tolu 
balsam  and  iodoform,  e.g.,  are  applied  either  to  the  same 
or  different  nostrils  at  the  same  time,  they  cancel  each 
other  and  no  odor  is  sensed.  Other  substances  pro- 
duce mixed  odors  that  may  or  may  not  be  analyzed 
into  their  components.  Xylol  and  turpentine  fuse  to 
form  a  new  odor  and  many  others  can  be  mentioned. 
Certain  of  these  mixed  odors  are  given  off  by  simple 
substances,  as  can  be  shown  by  the  fatigue  test.     Thus 


I 


ORGANIC    SENSATIONS  1 97 

if  propionic  acid  be  smelled  for  some  time,  the  original 
odor  will  lose  one  of  its  components  and  assume  a  dif- 
ferent quality. 

REFERENCES 

Ladd-Woodworth  :  Principles  of  Physiological  Psychology,  pp. 

304-309. 
ZwAARDEiiAAKER :  Physiologie  des  Geruchs,  1895. 
Titchener:  Textbook  of  Psychology,  pp.  1 14-128. 

Organic  Sensations 

Kinaesthetic  Sensations.  —  To  these  traditional  five 
senses  of  man,  modern  science  has  added  a  number  of 
others.  One  of  the  most  important  is  the  kinaesthetic, 
the  sense  by  which  we  appreciate  the  movements  of  our 
own  members.  The  muscle  sense  played  a  considerable 
part  in  the  English  psychology  of  the  last  century,  — 
Thomas  Brown  and  the  Mills  made  use  of  it,  —  but  the 
first  experimental  work  of  importance  on  the  subject 
was  carried  on  by  Goldscheider  in  the  late  eighties  of 
the  last  century.  Goldscheider  adduced  evidence  that 
the  more  dehcate  sensitivity  to  movement  was  in  the 
joints  rather  than  in  the  muscles,  as  had  been  earlier 
supposed.  His  main  bit  of  evidence  for  this  was  that 
the  sensation  of  movement  is  markedly  diminished  if 
an  induction  current  is  passed  through  the  joint  as  the 
member  is  bent.  Evidently  there  are  three  possible 
sources  of  sensation  for  movement,  the  external  skin, 
which  must  be  wrinkled  at  the  joint  as  it  bends,  the 
muscles  and  tendons  which  are  known  to  be  well  sup- 
plied with  sensory  endings,  and  the  joint.  Goldscheider 
assumed  on  the  basis  of  his  experiments  that  the  joint 


198  FUNDAMENTALS    OF   PSYCHOLOGY 

surfaces  were  the  organs  in  spite  of  the  fact  that  there 
are  known  to  be  no  sensory  nerves  ending  on  the  joint 
surface,  and  that  an  experiment  that  he  made  himself 
indicated  that  the  membrane  on  the  joint,  the  synovial 
membrane,  had  a  very  sHght  sensitivity. 

By  anaesthetizing  these  possible  sources  of  sensation 
one  after  another,  it  is  possible  to  determine  their  order 
of  importance  in  making  known  the  movements.  Ex- 
periments are  made  by  placing  the  member  to  be  tested, 
usually  the  forearm,  on  a  hinged  board,  with  the  joint 
over  the  hinge,  and  then  raising  the  board  until  the 
movement  is  first  noticed.  The  least  movement  of  the 
arm  that  can  be  appreciated  is  about  half  a  degree. 
If  the  external  skin  be  anaesthetized,  this  will  not  be 
changed.  The  skin,  then,  must  be  less  important  than 
the  internal  sense  organs.  Goldscheider  found  that  if 
an  induction  current  be  passed  through  the  joint,  there 
must  be  a  considerable  increase  in  the  movement  be- 
fore a  sensation  is  produced.  He  regarded  this  as  evi- 
dence that  the  joints  were  essentially  the  organs  of 
movement.  The  writer  repeated  the  experiments  and 
found  that  although  when  the  elbow  or  knee  joint  was 
anaesthetized  by  passing  an  induction  current  through 
it  the  sensitivity  for  movement  was  reduced,  it  was 
also  reduced  quite  as  much  when  an  induction  current 
was  passed  through  the  wrist  or  ankle  joint,  or  the 
muscles  near  them,  and  still  more  reduced  when  passed 
through  both  at  the  same  time.^  From  this  it  seems  that 
the  essential  organs  in  the  appreciation  of  movement 

'  Pillsbury,  Does  the  Sensation  of  ]\rovcment  Originate  in  the 
Joint?     Amer.  Journ.  of  Psychology,  igor.      346-353. 


ORGANIC    SENSATIONS  1 99 

are  the  muscles  and  tendons  with  the  sensory  nerve 
ends  that  are  embedded  in  them.  These  results  have 
recently  been  confirmed  by  von  Frey.^  This  hypothesis 
is  strengthened  by  the  histological  evidence  that  the 
joint  surfaces  are  bare  of  sense  organs,  and  by  the  fact 
that  careful  observation  indicates  that  the  movement 
is  ordinarily  felt  either  in  the  wrist  or  fingers.  Instead, 
then,  of  regarding  the  kinaesthetic  impressions  as  com- 
ing primarily  from  rubbing  of  joint  surfaces,  we  may 
regard  the  excitation  of  the  sensory  endings  in  the 
muscles  and  tendons  by  the  contraction  of  the  muscle 
or  the  stretching  of  the  tendon  as  the  source  of  our  sen- 
sations of  movement.  To  this  may  be  added  as  a  sub- 
sidiary factor  the  wrinkling  of  the  joint  capsule,  which 
also  contains  sensory  endings. 

These  kinaesthetic  impressions  play  a  very  large  part 
in  our  mental  life.  It  is  of  course  important  to  know 
where  the  different  members  of  the  body  are  at  any 
moment.  In  addition  to  this  the  kinaesthetic  sensations 
contribute  very  largely  to  the  coloring  of  other  experi- 
ences ;  they  guide  the  different  movements  and  consti- 
tute an  important  element  in  the  emotions.  We  shall  have 
occasion  to  make  use  of  them  often  in  the  later  chapters. 

The  Static  Sense.  —  Closely  related  to  the  kinaes- 
thetic sense  in  function  is  the  sense  of  equihbrium.  This 
is  also  a  sense  of  relatively  recent  discovery.  In  1872 
Crum  Brown,  Breuer,  and  Mach  independently  reached 
the  conclusion  that  the  portion  of  the  inner  ear  not 
used  in  hearing,  the  so-called  vestibular  portion  of  the 

^Von  Frey,  Studien  iiber  den  Kraftsinn.  Zeitschr.  f.  Eiologie, 
1913.     129-154. 


200  FUNDAMENTALS    OF   PSYCHOLOGY 

ear,  is  closely  connected  with  keeping  the  balance,  and 
with  the  appreciation  of  the  movements  of  the  body  as 
a  whole.  The  evidence  accumulated  since  is  altogether 
convincing.  The  organs  involved  are  the  sacculus,  the 
utriculus,  and  the  semicircular  canals,  named  in  order 
from  the  vestibule.  The  sacculus  is  a  membranous 
sack  floating  in  the  lymph  contained  in  an  enlargement 
of  the  bony  labyrinth.  This  opening  communicates 
with  the  vestibule,  and  the  lymph  is  continuous  with 
the  lymph  of  the  cochlea.  A  branch  of  the  vestibular 
nerve  enters  the  sacculus,  and  ends  in  hair  cells.  Among 
the  hairs  are  small  crystals  of  calcium  carbonate,  the 
otoliths.  The  utriculus  is  a  similar,  somewhat  larger 
sack  in  another  cavity  connected  with  the  sacculus  by 
a  small  opening.  The  nerve  endings  are  similar  to  those 
of  the  sacculus.  From  the  utriculus  extend  the  semi- 
circular canals,  one  in  each  plane  of  space.  They  have 
two  openings  into  the  utriculus,  making  possible  a  move- 
ment of  the  lymph  through  the  complete  semicircle. 
Near  one  opening  of  each  canal  into  the  utriculus  are 
small  swelhngs,  the  ampullae.  In  these  end  the  branches 
of  the  vestibular  nerve  that  go  to  each  canal.  The  nerves 
end  in  long  hairs  that  protrude  into  the  lymph  of  the 
ampullae.  The  different  branches  of  the  vestibular 
nerve  unite  with  each  other  and  join  the  cochlear  branch 
to  constitute  the  eighth  nerve.  In  the  brain  stem  the 
two  branches  have  separate  nuclei.  The  nucleus  of  the 
vestibular  branch  has  connections  primarily  with  the 
cerebellum  and  with  the  nuclei  of  the  motor  nerves  of 
the  eye. 
The  evidence  that  the  function  of  these  organs  is 


ORGANIC   SENSATIONS  201 

primarily  to  keep  the  balance  is  now  manifold.  The 
earlier  investigators  proved  that  sectioning  a  semicir- 
cular canal  in  a  pigeon  disturbed  its  balance  and  the 
tonus  of  its  muscles,  and  at  first  made  it  stand  with  the 
head  drawn  to  one  side.  It  was  also  shown  that  passing 
a  strong  electric  current  through  the  ears  would  produce 
a  turning  of  the  head.  Studies  of  patients  with  diseased 
vestibular  organs  showed  characteristic  loss  of  some 
one  function  according  to  the  part  affected  and  the  length 
of  time  the  disease  had  lasted.  Many  of  the  deaf  are 
also  defective  in  keeping  the  equilibrium.  If  one  reg- 
isters the  movements  they  make  when  standing  erect 
with  eyes  closed,  it  is  found  that  they  sway  much  more 
than  the  normal  individual.  It  is  also  found  that  about 
half  the  deaf  do  not  have  the  compensating  eye  move- 
ments, i.e.  the  movements  of  the  eyes  that  make  the 
eyes  turn  in  the  direction  opposed  to  that  taken  by  the 
head,  that  permit  the  eyes  to  fixate  a  point  reflexly 
in  spite  of  movements  of  head  or  body.  In  many 
cases  the  vestibular  portion  of  the  ear  is  normal 
when  the  cochlea  is  affected. 

Streeter  has  shown  that  if  he  destroys  the  vestibular 
region  in  the  tadpole,  the  frog  that  develops  from  it 
has  no  sense  of  position,  is  as  hkely  to  swim  on  its  back 
or  side  as  right  side  up.  Kreidl  inserted  iron  filings  in 
the  otocysts  of  the  crayfish  when  they  were  opened  by 
the  shedding  of  the  shell,  in  place  of  the  particles  of 
sand  that  normally  find  their  way  into  the  cavities  at 
that  time.  After  the  new  shell  was  grown  he  found  that 
if  he  brought  a  magnet  over  the  crayfish  they  would 
at  once  turn  and  swim  on  their  backs.     Evidently  the 


202  FUNDAMENTALS    OF   PSYCHOLOGY 

attraction  of  gravitation  for  the  sand  particles  had  been 
replaced  by  the  magnetic  attraction  for  the  iron  fihngs. 
These  various  Hnes  of  experimental  evidence,  together 
with  the  probabihty  raised  by  the  close  central  connec- 
tion of  the  nerve  with  the  cerebellum  and  with  oculo- 
motor centres,  are  conclusive  proof  that  the  vestibule 
contains  the  organ  for  the  static  sense,  and  is  the  source 
of  reflexes  for  many  eye  movements  and  for  keeping  the 
balance,  as  well  as  for  keeping  the  general  tonus  of  the 
muscles. 

The  Organs  of  Equilibration  and  their  Stimuli.  — 
The  mechanism  of  the  stimulation  of  the  sense  organs 
may  be  made  out  in  a  measure  from  the  experimental 
data  and  the  structure  of  the  organs.  Movements  of 
the  body  as  a  whole  probably  stimulate  the  sacculus  and 
utriculus  primarily.  As  the  body  moves  forward,  the 
otoHths  are  left  behind  for  a  moment  through  their  own 
inertia  and  so  move  the  hairs  and  stimulate  the  nerves. 
This  excitation  occurs  only  at  the  start ;  soon  the  oto- 
Kths  take  on  the  motion  of  the  body  and  no  further 
excitation  occurs.  The  opposite  stimulation  is  given 
as  the  motion  ceases ;  the  otoliths  continue  to  move  for- 
ward under  their  own  inertia  for  a  time  and  produce  the 
same  effect  as  if  the  person  were  starting  backward. 
This  may  be  noticed  as  a  train  comes  to  a  stop.  For 
an  instant  one  seems  to  be  starting  backwards.  Going 
up  or  down,  as  in  an  elevator,  also  displaces  the  otoliths 
and  gives  the  corresponding  sensations.  Movements 
of  rotation  and  of  turning  the  head  in  the  different  planes 
affect  the  semicircular  canals.  The  hairs  in  the  am- 
pullae are  probably  stimulated  by  the    movements   of 


ORGANIC    SENSATIONS  203 

the  liquid  and  these  stimulate  the  corresponding 
nerves. 

It  is  a  question  whether  these  excitations  give  rise  to 
a  sensation  of  their  own  or  whether  they  merely  excite 
reflexes  and  these  reflexes  are  appreciated.  Violent 
excitations  produce  sensations  of  giddiness  and  finally 
nausea  and  vomiting,  as  in  seasickness.  Slighter  ex- 
citations only  call  out  movements  of  the  eyes  and  the 
movements  required  to  keep  the  balance.  The  same 
sensations  of  giddiness  and  even  nausea  may  be  pro- 
duced by  rapid  irregular  movements  of  the  eyes  without 
movements  of  the  body.  All  of  this  speaks  for  the  view 
that  the  sensation  of  giddiness  is  not  a  true  sensation 
of  the  vestibular  nerve,  but  rather  a  sensation  from  the 
alimentary  canal,  due  to  reflexes  excited  by  the  organs 
of  equihbrium.  On  this  theory  the  vestibular  nerve 
excites  no  peculiar  sensation,  but  serves  to  adjust  the 
dift'erent  muscles  of  the  body,  including  primarily  the 
eye  muscles,  to  the  various  movements  of  the  body. 
The  sensations  arise  from  the  reflexes  when  they  become 
intense.  It  should  be  noted  that  visual  sensations, 
kinaesthetic  sensations,  and  sensations  due  to  displace- 
ment of  the  large  visceral  organs  also  aid  in  keeping 
the  balance  and  in  appreciating  the  movements  of  the 
body.  The  deaf  who  have  lost  the  sensitivity  of  the 
vestibule  can,  by  means  of  these  other  organs,  still  retain 
the  balance,  though  less  accurately. 

Hunger  and  Thirst,  General  Sensibility.  —  Of  the 
sensations  from  the  inner  organs,  hunger  and  thirst 
probably  bulk  largest  in  the  daily  life  of  man.  Hunger 
has  been  recently  investigated  by  Carlson  and  by  Can- 


204  FUNDAMENTALS    OF   PSYCHOLOGY 

non.^  They  find  in  man  and  dogs  that  it  is  a  compara- 
tively transient  accompaniment  of  the  deprivation  of 
food.  During  a  period  from  three  to  five  days  after 
food  is  stopped,  the  sensations  become  continually 
weaker  and  gradually  practically  disappear.  They  are, 
however,  rearoused  by  sight  of  food  or  by  anything  that 
suggests  food.  The  sensations  were  found  to  be  due  to 
contractions  of  the  walls  of  the  stomach.  Records  of 
these  contractions  were  taken  by  swallowing  a  rubber 
sack  or  balloon  with  tube  attached  which  could  be  in- 
flated to  fill  the  stomach,  and  then  registering,  upon  a 
revolving  drum,  the  compressions  of  the  air  in  the 
balloon.  These  contractions  are  particularly  vigorous 
when  hunger  is  keenest,  and  in  general  run  parallel  to 
the  sensations.  Thirst  has  its  seat  in  the  back  of  the 
throat.  It  is  apparently  due  to  the  drying  of  the  mem- 
brane there.  It  may  be  reUeved  by  laving  the  back  of 
the  mouth  with  citric  acid  or  by  taking  Hquid  into  the 
system,  either  through  the  mouth,  through  an  artifi- 
cial opening  into  the  stomach,  or  directly  into  the 
circulation.  Each  of  these  processes  leads  to  the  mois- 
tening of  the  membrane  in  question.  In  addition  to  the 
qualities  of  sensation  discussed,  there  are  a  vast  number 
of  other  sensations  which  fuse  in  the  general  complex 
of  organic  sensibility.  It  is  useless  to  speculate  upon 
their  quality  or  their  number.  With  the  advance  of 
science  others  will  undoubtedly  be  separated  from  the 
mass  and  be .  recognized  as  separate  senses ;  some 
already  have  names  ascribed  to  them  in  popular  speech. 

^  Cannon,  The  Physiological  Processes  in  Pain,  Hunger,  Fear,  and 
Rage. 


SENSATION  —  SPECIFIC    ENERGIES  205 

Of  these,  the  more  external  of  tickling,  pins  and  needles, 
itching,  have  been  explained  in  different  ways ;  pins 
and  needles  by  changes  in  circulation ;  tickhng  by 
contractions,  in  the  skin  muscles,  survivals  of  the  fully 
developed  skin  muscles  in  animals,  or,  by  certain  authors, 
as  due  to  stimulation  of  tickle  spots,  a  fifth  form  of  sen- 
sory spot  in  the  skin.  Xo  one  of  the  explanations  can 
be  regarded  as  more  than  h}^othetical.  The  internal 
sensations  are  even  less  known  and  few  if  any  distinc- 
tive names  can  be  given.  Such  names  as  are  given 
refer  to  particular  complexes,  such  as  those  present  in 
the  different  emotions,  rather  than  to  specific  sensations. 
Some  of  these  inner  sensations  are  of  the  same  quahty 
as  the  cutaneous  sensations,  and  are  always  fused  with 
sensations  from  the  contraction  of  various  muscles. 
They  are  most  frequently  fused  into  the  vague  feeHngs 
of  well-being  or  ill-being,  and  are  attended  to  only  as 
signs  of  health  or  of  general  bodily  state. 

The  Doctrine  of  Specific  Energies.  —  A  final  problem 
is  the  bearing  of  the  results  so  far  discussed  upon  the 
doctrine  of  specific  energies.  We  have  found  that  law 
convenient  as  an  introduction  to  the  study  of  sensation, 
and  have  used  it  as  a  guide  throughout.  But  it  is  now 
time  to  determine  how  accurately  our  hypothesis 
harmonizes  with  the  facts.  The  doctrine  for  conven- 
ience may  be  di\dded  into  dift'erent  parts,  i.  A  nerve 
end  when  stimulated  at  all  always  gives  rise  to  its  own 
pecuHar  sensation.  2.  There  are  as  many  nerve  ends 
as  there  are  specifically  different  sensations.  3.  The 
quality  of  the  sensation  depends  upon  the  character 
of  the  end  organ  rather  than  upon  the  nature  of  the 


206  FUNDAMENTALS    OF   PSYCHOLOGY 

stimulus.  If  we  examine  these  phases  of  the  doctrine 
one  by  one,  we  find  that  the  first  holds  so  far  as  it  is 
possible  to  test  it  at  all  accurately.  It  applies  to  the 
retina,  to  the  end  organs  on  the  skin  and  on  the  tongue, 
less  certainly  to  the  olfactory  organ.  In  discussing 
the  problem  we  distinguish  adequate  and  inadequate 
stimuH.  An  adequate  stimulus  is  one  that  excites  the 
organ  in  greatest  perfection.  Light  is  an  adequate  stimu- 
lus for  the  eye,  sound  waves  for  the  ear,  etc.  Adequate 
stimuH  give  the  full  number  of  sense  quahties  of  which 
the  organ  is  capable.  Other  stimuH  are  inadequate. 
The  electric  current  is  an  inadequate  stimulus  for  all 
senses,  pressure  an  inadequate  stimulus  for  the  eye,  etc. 
Each  of  the  sense  organs  mentioned  may  be  excited  by 
one  or  more  inadequate  stimuli,  and  when  excited  re- 
sponds with  a  sensation  of  the  quahty  peculiar  to  that 
sense.  The  number  of  stimuli  that  will  excite  the  organ 
and  the  intensity  of  stimulation  required  vary  from 
organ  to  organ  and  for  the  different  sense  qualities  within 
the  same  organ.  The  sensation  that  arises  when  the 
organ  is  stimulated  also  shows  various  degrees  of  ap- 
proximation to  those  excited  by  the  adequate  stimulus. 
On  the  skin,  most  of  the  organs  may  be  excited  by  sev- 
eral stimuli  and  give  approximately  the  same  quality 
as  that  produced  by  the  adequate  stimulation.  The 
olfactory  endings  are  excited  with  difficulty  and  then, 
so  far  as  is  known,  only  by  electrical  stimuli,  and  the 
resulting  quality  is  very  uncertain.  The  location  of 
the  organ  may  account  in  part  for  the  uncertainty  of 
the  result.  The  retina  has  an  intermediate  position 
in  both  respects.     Mechanical  and  electrical  stimuli  at 


SENSATION  —  SPECIFIC   ENERGIES  207 

least  will  affect  it,  and  they  produce  several  sensory 
responses,  but  not  the  variety  or  delicacy  of  effect 
produced  by  the  Kght  waves.  While  the  law  will  not 
hold  wdth  the  completeness  that  a  firm  believer  might 
wish,  still  it  can  be  said  in  general  that  sense  organs  may 
be  affected  by  various  stimuli,  and  when  they  respond, 
if  they  respond  at  alt,  the  quahty  is  that  ordinarily 
given  by  that  organ  rather  than  the  quality  produced  by 
the  stimulus  in  the  organ  for  which  it  is  the  adequate 
stimulus. 

The  second  law  is  less  definitely  demonstrable.  Ex- 
cept on  the  skin,  one  cannot  prove  that  each  sense  qual- 
ity has  a  separate  nerve  end.  From  what  we  know  of 
the  eye,  the  cones  probably  have  more  than  one  sense 
quahty,  and  while  one  might  assume  that  there  are 
different  chemical  substances  in  each  cone,  it  is  hardly 
hkely  that  there  are  different  nerve  ends.  A  case  might 
be  made  out  for  separate  taste  buds  for  each  quaHty; 
there  is  sHght  evidence  for  separate  organs  for  each 
odor.  In  hearing,  the  Helmholtz  theory  depends  for  its 
truth  upon  the  law  rather  than  substantiates  it.  Strictly, 
then,  the  statement  that  there  are  as  many  qualities  as 
there  are  sense  organs  and  no  more  holds  only  for  cer- 
tain senses,  and  is  to  be  regarded  rather  as  a  convenient 
guide  to  the  discussion  of  sensation  than  as  a  fully  sub- 
stantiated fact.  The  third  principle,  that  the  quahty  of 
sensation  depends  upon  the  sense  organ  excited  rather 
than  upon  the  stimulus,  holds  approximately.  Ade- 
quate stimuH  excite  the  organ  at  a  slighter  intensity  and 
give  a  richer  quahty  in  most  of  the  sense  organs.  Never- 
theless if  one  were  to  decide  between  the  receiving  organ 


208  FUNDAMENTALS    OF   PSYCHOLOGY 

or  the  external  stimulus  as  the  determinant  of  the  sen- 
sory quality,  the  receiving  organ  must  be  given  the 
more  important  part. 

There  is  also  a  question  whether,  granted  that  the 
sensations  depend  upon  the  specific  characteristics  of 
the  nervous  system,  the  determinants  of  the  quality 
are  to  be  found  in  the  sense  organ  or  more  centrally  in 
the  nerves  or  their  central  connections.  The  evidence 
is  conflicting  from  sense  to  sense.  According  to  Nagel  ^ 
there  is  no  good  evidence  that  colors  can  be  excited 
except  from  the  retina.  Cutting  the  optic  nerve  or 
turning  the  eyes  sharply  to  one  side  or  the  other  gives 
rise  to  sensations  of  hght,  but  he  thinks  both  probably 
due  to  the  accompanying  pull  upon  the  retina.  Sen- 
sations of  taste  are  with  difficulty  or  not  at  all  excited 
by  inadequate  stimuli  upon  the  tongue,  while  mechani- 
cal stimuli  upon  the  chorda  tympani  where  it  passes 
through  the  middle  ear  arouse  them  certainly  and  at 
comparatively  slight  intensities.  In  the  skin  it  is  appar- 
ently the  end  organ  that  gives  the  peculiar  quality. 
Pressure  upon  the  ulnar  nerve  gives  sensations  but  not 
of  the  distinct  qualities  that  may  be  aroused  from  the 
skin.  One  cannot  decide  definitely  between  sense 
organ  and  the  more  central  regions.  Of  the  central 
nervous  organs,  it  seems  that  the  nerves  themselves  are 
relatively  indifferent.  They  conduct  in  either  direc- 
tion, and  sensory  nerves  may  be  made  to  carry  motor 
impulses  by  giving  them  connections  with  motor  struc- 
tures. Whether  the  cortical  centres  have  a  specific 
function  is  still  an  open  question.     It  has  been  assumed 

1  Nagel,  Handbuch  der  Physiologic,  vol.  iii,  pp.  1-15. 


WEBER'S   LAW  209 

by  many  authorities  that  the  qualities  of  sensation  de- 
pend upon  the  parts  of  the  cortex  excited.  No  actual 
evidence  for  it  has  been  collected  and  it  seems  improb- 
able that  it  could  be  obtained.  In  general,  it  may  be 
said  that  the  doctrine  of  specific  energies  of  sensory  ends 
lacks  much  of  complete  demonstration,  but  that  what  data 
we  have  tends  to  support  rather  than  to  refute  it.  On 
disputed  points  evidence  is  wanting  rather  than  opposed. 

Studies  in  Sensation  Intensities.  —  Weber's  Law 

Sensation  intensities  offer  an  entirely  different  prob- 
lem from  qualities.  QuaKties,  as  we  have  seen,  are  ordi- 
narily named,  may  be  referred  in  some  cases  to  sense 
organs,  offer  points  of  discrimination  that  may  be  re- 
called in  memory,  —  in  general  stand  out  for  themselves. 
Intensities,  on  the  contrary,  have  none  of  these  char- 
acteristics. We  think  of  a  sound  as  very  faint,  mod- 
erately or  very  loud,  but  that  is  all.  Intensities  have 
no  real  designations,  and  cannot  be  remembered  at 
all  accurately.  It  is  perhaps  not  one-tenth  as  bright 
in  this  room  to-day  as  it  was  when  last  the  sun  shone, 
but  you  do  not  appreciate  the  difference  accurately. 
You  think  of  this  as  a  moderately  dark  day,  but  have 
little  idea  how  much  darker  than  yesterday.  The  same 
holds  of  weights.  Most  persons  have  great  difficulty  in 
deciding  whether  a  package  of  an  unknown  substance 
weighs  one  pound  or  two,  and  would  be  altogether  at  a 
loss  to  decide  whether  more  energy  was  exerted  on  the 
ear  by  a  telephone  held  close  to  it  or  by  a  steam  whistle 
at  a  distance. 


2IO  FUNDAMENTALS   OF  PSYCHOLOGY 

Measurements  of  Sensation.  —  It  has  long  been  a 
problem  among  psychologists  as  to  how  intensities  may 
be  treated.  The  modern  discussion  of  the  matter  may 
be  said  to  date  back  to  Fechner,  who  thought  it  would 
be  possible  to  obtain  a  unit  for  the  measurement  of  sen- 
sation intensities  analogous  to  those  employed  in  physi- 
cal measurements.  His  assumption  was  that  the  barely 
distinguishable  sensation  difference,  the  difference  limen 
as  he  called  it,  might  be  made  a  unit  and  any  given  sen- 
sation might  be  measured  in  terms  of  the  number  of 
such  units  it  contained.  This  assumed  that  the  only 
judgments  that  may  be  passed  on  intensities  are  that 
the  sensation  is  or  is  not  present,  or  that  it  is  greater  or 
less  than  another.  The  amount  of  sensation  intensity 
that  may  be  just  noticed,  the  limen,  was  chosen  by  Fech- 
ner as  the  zero  point  in  his  scale.  If  one  should  start 
with  the  faintest  sensation  that  comes  to  consciousness, 
and  determine  the  addition  that  can  just  be  noticed,  the 
liminal  sensation  might  be  called  sensation  number 
one ;  the  just  noticeably  different  sensation,  sensation 
number  two ;  and  if  one  should  continue  the  process,  it 
would  be  possible  to  determine  the  entire  number  of 
differences  that  could  be  noted  in  the  series  of  sensa- 
tions, and  thus  the  entire  number  of  sensation  intensities 
in  any  sense  department.  It  would  also  be  possible  to 
measure  any  sensation  by  the  number  of  these  unit 
intensities  that  were  contained  in  it.  Unfortunately, 
however,  the  facts  are  by  no  means  so  simple  as  this 
theory  would  assume.  The  least  intensity  that  can  be 
noticed  is  not  fixed  even  for  the  same  individual,  and  the 
number  of  units  that  can  be  noticed  is  also  variable. 


Weber's  law  211 

In  consequence,  this  scheme,  attractive  as  it  is  in  theory, 
has  never  been  and  apparently  cannot  be  applied  in 
practice. 

Weber's  Law.  —  Out  of  the  very  large  number  of 
experiments  devoted  to  these  measurements,  a  law  has 
developed  that  is  of  great  interest.  Very  briefly,  it 
has  been  found  that  the  size  of  the  just  noticeable  incre- 
ment is  not  the  same  for  all  intensities,  but  increases  with 
the  absolute  intensity  of  the  stimulus,  and  bears  a  con- 
stant ratio  to  that  intensity.  Thus  Weber  found  that 
if  a  weight  of  32  ounces  were  lifted,  it  could  be  noted 
that  30  ounces  was  just  less,  while  if  32  drachms  were 
lifted,  30  drachms  could  just  be  noticed  to  be  different. 
A  difference  of  a  fifteenth  of  the  total  weight  could  be 
noted  whether  the  units  were  ounces  or  drachms.  These 
relatively  crude  experiments  have  been  repeated  and 
improved  upon  by  a  number  of  later  workers,  Fechner 
in  particular,  and  show  the  same  general  law.  The 
fraction  of  the  total  intensity  that  may  be  just  noticed 
varies  from  one  sense  to  another,  but  holds  with  fair 
accuracy  for  the  same  sense.  The  values  range  from 
approximately  ro^  for  sight  to  one-third  or  one-fourth 
for  smell.  In  giving  these  values,  it  should  not  be 
assumed  that  the  just  noticeable  difference  is  absolutely 
constant  even  under  constant  objective  and  subjective 
conditions,  or  under  conditions  that  are  as  nearly  constant 
as  can  be  obtained,  differences  in  the  order  in  which 
stimuli  to  be  compared  are  given,  in  the  degrees  of  atten- 
tion at  different  times,  and  in  the  way  in  which  the  sug- 
gestions that  may  be  given  unintentionally  may  work, 
all  have  an  influence  upon   the  determination  of  the 


212  FUNDAMENTALS    OF   PSYCHOLOGY 

difference  limen.  In  consequence,  it  is  not  often  that 
two  consecutive  experiments  will  give  the  same  result. 
All  values  given  are  averages  obtained  with  the  same  in- 
dividual, and  where  several  values  are  given  it  is  assumed 
that  the  two  are  extremes  for  the  subjects  used.  Occa- 
sionally the  values  obtained  from  different  observers 
will  be  averaged,  but  this  is  not  at  present  regarded  as 
advisable.  The  results  are  not  to  be  regarded,  as  in 
physics,  constant  values  that  are  obscured  by  the  vary- 
ing conditions  of  observations,  but  as  fundamental 
differences  due  to  the  differences  between  individuals. 

Departures  from  Weber's  Law.  —  It  is  also  true  that 
the  fraction  varies  for  the  different  absolute  intensities. 
It  is  always  greater  for  the  extreme  intensities,  and  even 
within  what  may  be  called  the  mean  values,  there  is 
often  a  gradual  change.  The  first  fact  can  be  seen  in 
many  of  the  simple  phenomena  of  daily  life.  The  increase 
in  the  least  noticeable  difference  at  maximum  intensities 
is  illustrated  in  the  difficulty  in  reading  when  the  sun 
is  shining  on  the  page,  as  the  difficulty  in  reading  in 
faint  light  illustrates  the  increase  of  the  relative  differ- 
ence at  the  lower  range  of  intensities.  The  relative 
amount  of  light  reflected  and  absorbed  is  the  same  at 
all  intensities,  but  the  relative  difference  that  may  be 
discriminated  is  much  greater  at  the  extremes  of  absolute 
intensities.  Were  relative  differences  discernible  with 
equal  ease  at  all  intensities,  one  could  read  as  readily 
by  moonlight  as  by  electric  light,  and  in  the  glare  of  the 
sun  as  well  as  in  the  shade. 

The  values  that  have  been  obtained  in  the  more  im- 
portant senses  range  for  vision  from  ^to  -rkz  for  different 


\nt:ber  s  LAW  213 

observers  and  different  intensities.  For  hearing,  Wien, 
using  telephone  tones,  obtained  a  fraction  of  i  to  i; 
for  pressures,  values  have  been  obtained  from  ^o  to  ^, 
depending  upon  the  part  of  the  body  stimulated.  Lifted 
weights  give  a  much  smaller  value  than  passive  pressure, 
from  2V  to  XFO-?  according  to  Biedermann  and  Lowit, 
according  to  Weber  ■^.  Taste,  smell,  and  temperature, 
all  offer  difficulties  in  the  technique,  and  the  results  are 
correspondingly  unsatisfactory.  The  values  of  the 
fraction  for  these  senses  are  generally  given  as  ranging 
from  i  to  i-  The  results  of  the  investigations  of  the 
least  intensities  that  can  be  perceived,  the  absolute 
sensation  Hmen,  have  also  been  determined  for  certain 
senses  ^nth  a  satisfactory  degree  of  accuracy.  For  sight 
and  sound  the  values  can  be  given  in  terms  of  absolute 
units.  Langley  found  that  the  eye  was  sensitive  to 
Hght  waves  that  exerted  an  energy  of  .00000003  erg. 
Wien  found  that  the  ear  would  respond  to  still  smaller 
values :  from  .000004  erg  for  tones  of  50  VD  per  second 
to  .0000000000000005  erg  fc)^  tones  of  3200  VD  per 
second.  For  pressure,  the  most  reliable  results  are 
those  given  by  von  Frey,  who  worked  ^^ith  indi\'idual 
pressure  spots.  He  found  that  the  values  were  fairly 
constant  for  different  spots,  from  .5  to  4  grams  per  square 
millimetre  of  surface  stimulated.  \^alues  obtained  for 
other  senses  have  relatively  Httle  meaning,  as  they  can- 
not be  stated  in  terms  of  energy. 

Theories  of  Weber's  Law.  —  It  can  be  asserted,  then, 
that  \\'ithin  Hmits  Weber's  law  holds.  '^Dift'erences  in 
two  stimuH  are  noticed  more  easily  when  the  absolute 
stimuli  are  low  than  when  thev  are  high,  and  the  addition 


214  FUNDAMENTALS    OF   PSYCHOLOGY 

that  can  just  be  appreciated  is  a  constant  fraction  of  the 
stimulus  already  present. .'  The  explanation  of  this  law 
falls  into  three  groups.  Wundt  holds  that  the  law  has 
a  purely  mental  basis,  that  it  is  but  one  expression  of  the 
general  law  of  relativity;  all  things  are  estimated  in 
terms  of  other  things  that  may  be  in  consciousness  at 
the  moment.  This  is  merely  a  restatement  of  the  law 
rather  than  an  explanation.  Fechner  regarded  the  law 
as  an  expression  of  the  general  relation  between  body  and 
mind.  These  were  two  phases  of  a  single  substance 
for  him,  Uke  the  inside  and  outside  of  a  circle,  and 
in  some  way  not  made  clear,  stimuli  that  increase  in  a 
geometrical  ratio  produce  an  increase  in  mind  in  an 
arithmetical  ratio.  A  third  theory,  developed  in  large 
degree  by  G.  E.  Miiller,  explains  the  law  as  due  to  the 
loss  in  intensity  that  a  nerve  impulse  undergoes  in  pass- 
ing through  the  nervous  system  itself.  That  such  a 
loss  does  take  place  is  suggested  by  the  experiments  of 
Waller  with  the  optic  nerve  and  retina  of  a  frog.  The 
current  of  action  of  the  nerve  excited  by  different  inten- 
sities of  light  upon  the  retina  was  measured  and  it  was 
found  that  the  current  of  action  was  related  to  the  in- 
tensities of  stimulus  in  the  arithmetical-geometrical 
ratio.  Miiller  asserts  that  the  more  intense  the  stimulus, 
the  more  opposition  is  offered  to  its  passage  through  the 
nervous  system,  and  in  consequence  the  more  is  lost, 
a  smaller  proportion  reaches  the  brain.  If  the  amount 
lost  —  and  so  the  amount  retained  —  is  proportional  to 
the  absolute  intensity  of  the  stimulus,  the  demands  of 
Weber's  law  are  satisfied.  Ebbinghaus  has  suggested 
that  this  increased  loss  can  ])e  explained  on  the  assump- 


weber's  law  215 

tion  that  there  are  in  the  nerve  chemical  substances 
which  decompose  with  different  degrees  of  difficulty. 
The  less  intense  stimuH  use  up  the  more  readily  decom- 
posable elements,  and  hence  produce  a  relatively  great 
effect  on  consciousness,  and  the  stimulus  must  exhaust 
an  increasingly  greater  amount  of  energy  in  affecting  the 
components  next  higher  in  the  degree  of  difficulty  of 
decomposition.  WTiatever  the  detailed  explanations, 
the  facts  available  indicate  that  the  law  is  due  to  the 
increasing  resistance  oft'ered  in  the  nervous  system  to  the 
transmission  of  the  more  intense  nerve  impulses,  that 
the  explanation  is  physiological  rather  than  psycho- 
physical or  purely  psychological.^ 

1  Titchener,  Manual  of  Psychology,   Instructor's  Manual.      Quan- 
titative. 


CHAPTER  VI 

IMAGES  AND  THE  LAWS  OF   CENTRALLY  AROUSED 
SENSATIONS 

Not  all  of  the  material  of  knowledge  comes  directly 
from  the  sense  organs.  Memory,  imagination,  and 
similar  processes  have  an  equal  part  in  our  mental  Hfe. 
From  the  objective  point  of  view,  behavior  is  controlled 
by  the  past  as  well  as  by  the  present  stimuli.  Pro- 
visionally we  may  treat  these  processes  as  if  they  were 
on  the  same  level  as  sensations.  We  may  think  of  them 
as  composed  of  definite  pictures  that  return  as  wholes 
or  are  recompounded  of  elements  derived  from  the  senses. 
Put  in  this  form,  our  present  problem  is  to  determine 
their  components,  and  to  discover  how  they  are  retained 
and  the  laws  that  govern  their  reappearance.  The 
primary  quaUties  are  like  sensations.  No  absolutely 
new  quahties  can  be  imagined.  Speaking  generally,  the 
qualities  of  memory  and  imagination  are  the  quaHties 
of  sensation.  It  is  possible  to  go  farther  and  assert 
that  if  one  is  to  have  images,  one  must  at  some  time 
have  had  sensations  of  the  corresponding  quality. 
Individuals  Wind  from  birth  cannot  imagine  colors; 
even  the  color  bhnd  cannot  picture  the  colors  which 
they  cannot  see.  The  same  holds  for  all  other  senses. 
This  has  led  to  the  general  acceptance  in  modern  times 
of  the  statement  that  all  images  are  derived  primarily 

216 


THE  LAWS  OF  CENTRALLY  AROUSED  SENSATIONS   21 7 

from  sensations.  This  simplifies  our  discussion  to  one 
of  asking  how  the  original  impressions  are  retained, 
how  they  may  be  rearoused  as  occasion  demands,  and 
how  their  qualities  differ  from  those  of  sensation. 

The  Nature  of  Retention.  —  The  question  how  mem- 
ories are  retained  must  be  preceded  by  asking  where  they 
are  retained.  Two  possibilities  have  been  suggested  in 
the  history  of  the  science :  one  that  they  are  retained  in 
mind  or  as  mental  states,  the  other  that  they  are  held 
in  the  nervous  system.  The  latter  is  at  present  gener- 
ally accepted.  The  theoretical  objection  to  thinking 
of  memories  as  being  retained  as  mental  states  is  that 
mental  states  are  by  definition  conscious,  while  there 
is  no  awareness  of  memories  until  they  are  revived. 
The  individual  cannot  tell  that  he  has  a  memory,  has 
no  awareness  of  the  amount  of  his  knowledge,  until  he 
tests  it  by  trying  to  call  up  particular  facts.  On  the 
positive  side,  the  evidence  that  remembering  is  in  some 
way  dependent  upon  the  nervous  system  comes  from 
pathology.  Numerous  cases  present  themselves  in 
which  loss  of  memory  is  one  of  the  prominent  symptoms, 
and  these  usually  show,  on  examination  of  the  brain, 
injuries  of  portions  of  the  cortex.  Destruction  of  the 
area  corresponding  to  a  sense  brings  mth  it  loss  of  the 
corresponding  memories ;  destruction  of  neighboring 
areas  or  of  paths  of  connection  with  other  portions  of 
the  cortex  also  destroys  or  impairs  the  effectiveness  of 
recall  of  the  images.  Studies  in  mental  pathology  have 
convinced  psychologists  that  memory  processes  are 
closely  dependent  upon  the  nervous  system. 

How  memories   are   retained   offers   more   room   for 


2l8  FUNDAMENTALS    OF   PSYCHOLOGY 

discussion.  Various  theories  have  been  suggested,  from 
the  crude  theory  of  the  Greeks  that  memories  were 
imprinted  on  the  brain  or  soul  as  the  impression  of  the 
seal  upon  wax,  to  the  scarcely  less  crude  anatomical 
theory  that  each  idea  had  a  cell  in  the  brain  in  which 
it  might  be  stored.  At  present  the  tendency  is  to  find 
analogies  that  shall  be  within  the  known  possibiUties 
of  the  nervous  system  and  not  to  make  the  explanation 
more  specific  than  the  known  facts  warrant.  The  ex- 
planation is  usually  in  terms  of  function,  of  what  the 
nervous  system  does  when  it  remembers,  rather  than 
of  how  it  holds  the  memories.  Hering  was  among  the 
first  of  the  modern  writers  to  suggest  this  method  of 
approach,  in  stating  that  memory  is  a  universal 
property  of  matter.  Any  change  that  may  be  suffered 
by  any  substance  tends  to  persist.  Garments  wrinkle 
where  they  have  been  often  creased;  i.e.  the  folds  tend 
to  persist.  Scars  on  the  skin,  even  nail  holes  in  boards, 
are  for  him  memories,  effects  left  on  the  substance  by 
changes  it  has  undergone.  In  the  organic  world  similar 
facts  are  particularly  striking.  The  physician  constantly 
finds  that  any  injury  or  disease  of  a  tissue  leaves  an 
effect,  —  it  is  weakened  for  a  considerable  time.  On 
the  other  side,  exercise  of  a  muscle  strengthens  it. 

Retention  and  Habit.  —  Habit  is  the  best  known 
expression  of  this  fact  in  connection  with  the  nervous 
system.  As  was  said  in  the  earher  chapter,  habit  may 
be  stated  in  its  most  general  form  to  be  a  change  induced 
in  a  tissue  as  a  result  of  doing  something.  This  leaves 
a  tendency  to  do  that  same  thing  more  easily.  Signs 
of  habit  formation  may  be  seen  even  in  the  unicellular 


THE    LAWS    OF   CENTR,\LLY   AROUSED    SENSATIONS       219 

organisms.  A  Stentor  responds  differently  after  a 
series  of  responses  have  failed  to  give  a  pleasant  result ; 
and  after  the  new  variation  has  been  repeated  several 
times,  that  vnR  tend  to  persist  for  some  time,  —  will 
become  a  habit.  In  the  higher  organisms  one  may 
think  of  both  habit  formation  and  of  memory  as  due 
to  persistence  of  changes  wrought  in  the  nervous  system 
by  its  action.  Habits  are  regarded  as  due  to  changes 
in  the  synapses  of  the  nervous  system.  Neurones  that 
have  acted  together  at  one  time  tend  to  act  together ; 
nervous  impulses  spread  from  the  one  first  active  to  the 
others,  owing  to  the  lessened  resistance  of  the  synapses 
that  intervene.  From  the  standpoint  of  Hering,  mem- 
ory in  its  essentials  has  the  same  basis.  It  is  primarily 
the  capacity  of  retaining  the  effects  of  one  action  of 
the  nervous  system  in  a  form  that  shall  make  probable 
its  repetition  at  some  time  in  the  future,  rather  than 
the  retaining  of  some  static  thing,  or  impression,  or 
idea.  Speaking  generally,  after  an  object  has  once 
been  seen,  a  tendency  persists  for  the  neurones  involved 
to  act  in  the  same  connections  again,  and  this  tendency 
leads  to  the  renewal  of  the  act  on  suitable  occasions. 
The  nervous  system  may  be  regarded  as  acting  in  a 
certain  way  at  the  time  of  perception,  and  of  repeating 
approximately  the  same  action  at  some  later  time. 
What  is  retained  is  probably,  as  in  habit,  a  tendency 
for  certain  elements  of  the  nervous  system  to  act  to- 
gether. This  tendency  is  due  to  a  lessening  of  the 
resistance  at  the  synapses  between  the  neurones  in- 
volved in  the  response.  Those  portions  of  the  cortex 
that  are  concerned  become  connected  as  a  unitary  whole, 


220  FUNDAMENTALS   OF   PSYCHOLOGY 

and  when  one  part  is  reexcited,  the  others  are  rearoused. 
What  is  left  is  merely  the  physical  or  chemical  change 
in  the  neurones.  Where  this  change  may  take  place 
can  be  determined  only  by  indirect  means  from  a  study 
of  diseased  conditions.  Present  evidence  makes  it 
probable  that  the  most  important  part  of  the  change  is 
found  in  the  sensory  areas  or  in  the  immediately  adjoin- 
ing association  areas,  although  no  portion  of  the  original 
nervous  tract  can  be  absolutely  excluded  from  consider- 
ation. 

After-image,  Memory  After-image,  and  Memory  Image. 
—  One  may  also  trace  an  analogy  between  memory  and 
simpler  forms  of  retention  or  prolongation  of  activity 
in  the  sense  organ.  In  vision,  gradations  may  be  traced 
between  the  after-image  and  the  more  extended  memory 
image.  If  one  look  for  a  moment  at  a  bright  color,  it 
will  continue  to  be  seen  for  a  fraction  of  a  second  after 
the  impression  has  been  removed.  This  after-image 
persists  from  two  to  five  seconds  as  an  image  that  is 
even  clearer  than  the  after-image  but  which  can  be 
shown  to  have  its  seat  in  the  cortex.  This  process  is 
known  as  the  primary  memory,  and  is  probably  partly 
identical  with  what  Fechner  called  the  memory  after- 
image. It  is  sufficiently  distinct  to  be  used  for  all  pur- 
poses in  place  of  the  actual  sensation,  and  is  for  many 
purposes  even  more  effective  than  the  sensation.  It 
may  be  regarded  as  due  to  a  persistence  of  the  activity 
of  the  cortical  elements  involved  in  sensation  in  just 
the  same  way  that  the  after-image  is  a  continuation 
of  the  action  of  the  retinal  elements.  They  possess 
an  even  greater  inertia  and  so  act  for  a  longer  time. 


TM   Li-Wi    ®F    fENTRALLT   AR®USED    SEXSATI®NS       221 

Miss  Martin  has  suggested  on  the  basis  of  Fechner's 
description  and  her  o^^tl  observ^ations  that  Fechner's 
memory  after-image  was  a  composite  of  the  after-image 
and  this  primary  memory ;  other  authorities  have  for 
the  most  part  identified  them.  Our  needs  are  satisfied 
with  the  recognition  that  both  the  after-image  and 
primary  memory  exist  and  are  due  to  practically  the 
same  conditions ;  one  is  a  persistence  of  the  visual 
processes  in  the  retina,  the  other  a  persistence  of  nervous 
action  in  the  cortex.  A  memory,  in  the  same  series, 
would  be  merely  the  reinstatement  of  the  primary 
memory  image  after  the  lapse  of  a  longer  or  shorter 
period.  The  same  ner\'ous  elements  may  be  assumed 
to  be  active  at  the  moment  of  recall  as  in  the  former 
case,  but  they  have  ceased  to  act  or  at  least  ceased  to 
produce  conscious  processes  for  a  longer  or  shorter  time, 
and  then  the  activity  is  in  some  way  reinstated.  The 
three,  after-image,  memory  after-image,  and  memory 
image,  all  exhibit  many  of  the  same  laws  and  may  be 
regarded  as  succeeding  steps  in  the  same  series.  The 
after-image  is  the  persistence  of  the  effect  in  the  sense 
organ ;  the  primary  memory,  a  persistence  of  the  activ- 
ity of  cells  in  the  cortex ;  memory,  a  reinstatement  of 
the  activity  in  the  cells  of  the  cortex  involved  in  the 
primary  memory. 

Reproduction.  —  Granted  the  retention  of  a  tendency 
to  act  again  in  a  way  once  acted,  it  is  next  in  order  to  ask 
how  or  when  this  reinstatement  of  the  activity  may 
take  place.  Two  occasions  are  ordinarily  recognized 
at  present,  the  perseverative  tendency  and  associa- 
tion.    The   former  is   simpler,    although   less   frequent 


2  22  rUNDA]\£ENTALS    OF   PSYCHOLOGY 

and  less  generally  accepted.  It  was  suggested  by 
Miiller  and  Pilzecker  that,  when  an  impression  has  been 
made,  the  nerve  cells  impressed  continue  active  for  a 
time,  and  in  consequence  the  corresponding  ideas  are 
likely  to  force  their  way  into  consciousness  when  noth- 
ing else  offers,  or  to  combine  with  other  processes  active 
at  the  same  time  in  the  production  of  more  complex 
processes.  This  they  call  perseveration.  Instances 
mentioned  are  the  reappearance  of  words  that  have 
been  heard  or  spoken  just  before  but  have  no  noticeable 
connection  with  the  course  of  thought ;  the  tendency 
of  tunes  to  '  run  in  the  head  ' ;  of  compHcated  practical 
problems  to  keep  returning  to  mind  on  all  occasions,  etc. 
This  tendency  seems  to  decrease  rather  quickly  at  first, 
but  some  slight  effect  is  supposed  to  persist  for  hours, 
and  when  the  original  event  is  interesting  or  the  impres- 
sion strong,  may  last  for  several  days.  It  is  assumed 
that  the  activity  of  the  nerve  cells  is  continuous,  but 
that  the  effect  of  their  activity  rises  to  consciousness 
only  now  and  again.  While  the  perseveration  tendency 
itself  is  unquestioned,  it  is  a  matter  of  dispute  how  long 
it  continues  and  whether  the  reappearances  after  a  lit- 
tle time  are  due  to  that  or  to  associations  that  have  not 
been  noticed. 

Laws  of  Association.  —  Association  as  an  explana- 
tion of  recall  can  be  traced  back  to  Aristotle  in  fairly 
accurate  formulation,  and  suggestions  of  it  are  found  in 
still  earlier  writers.  In  some  form  or  other  it  is  recog- 
nized by  all.  In  general,  this  doctrine  asserts  that  all 
reproduction  of  ideas  is  determined  by  the  connections 
that  have  been  formed  at  some  time  in  the  past.     Con- 


THE    LAWS    OF   CENTR.\LLY   AROUSED    SENSATIONS       223 

versely,  mental  processes  that  have  once  been  in  con- 
sciousness together,  tend  to  return  together.  An  empiri- 
cal study  of  learning  shows  that  words,  nonsense  syllables, 
or  objects  shown  together  or  in  immediate  succession 
tend  to  become  connected  and  when  one  is  presented 
again,  the  other  also  reappears.  Learning  the  name 
of  a  new  object,  connecting  a  person  with  a  place  where 
he  has  been  seen,  all  rote  learning  provide  instances 
of  this  sort.  On  the  physiological  side,  it  may  be  said 
that  all  learning,  all  experience,  is  of  things  in  their 
connections,  and  that  all  return  is  through  the  connec- 
tions formed  between  neurones  at  the  instant  of  learn- 
ing. When  a  group  of  neurones  was  active  at  the  time 
of  the  original  experience,  paths  of  connection  were 
formed,  synapses  were  opened  between  them,  and,  later, 
when  any  element  of  the  complex  is  aroused  in  any  way, 
the  impulse  tends  to  spread  over  the  partially  open 
s}Tiapses  to  the  other  elements  of  the  whole.  Associa- 
tion has  the  same  basis  as  habit,  but  need  not  end  in  a 
muscular  response.  As  was  said  in  the  beginning  of 
the  chapter,  all  learning  is  Kke  habit  formation ;  all 
learning  is  dependent  upon  formation  of  connections 
between  neurones,  —  nothing  can  be  learned  in  isola- 
tion. In  consequence,  association  is  at  once  the  funda- 
mental fact  in  learning,  in  retention,  and  in  recall. 
Learning  is  always  the  formation  of  connections  between 
neurones ;  retention  is  always  the  persistence  of  the 
connection,  or  the  partial  openness  of  synapses  which 
permits  an  impression  to  pass  from  one  to  the 
other  of  the  connected  elements ;  recall  is  the  rearousal 
of  the  whole  complex  by  some  one  of  the  elements  that 


224  FUNDAMENTALS   OF  PSYCHOLOGY 

may  be  stimulated  from  the  outside  world,   directly 
or  indirectly. 

While  from  the  standpoint  of  learning  it  may  be 
asserted  with  assurance  that  impressions  presented 
together  tend  to  return  together,  more  compHcation 
appears  when  one  attempts  to  determine  what  it  is 
that  has  brought  any  particular  old  experience  to  mind. 
Any  idea  that  returns  has  almost  always  been  asso- 
ciated with  several,  often  with  many  experiences,  and 
it  is  difficult  to  say  which  one  has  been  responsible 
for  its  recall ;  in  fact,  usually  a  number  of  factors  more 
or  less  remote  cooperate  in  the  recall.  Similarly,  if  some 
one  familiar  experience  be  presented,  it  is  not  possible 
to  say  with  certainty  what  idea  will  be  recalled  by  it. 
One  may  study  the  tendencies  to  recall  by  presenting 
a  number  of  words  to  a  subject,  and  letting  him  speak 
the  first  word  that  comes  to  mind.  If  the  same  list 
of  words  be  presented  to  a  number  of  persons  of  approxi- 
mately the  same  earfier  experience,  it  is  found  that  a 
large  number  of  the  responses  will  be  common  to  all. 
Kent  and  Rosanoff  secured  the  associations  called  out 
in  a  thousand  people  to  each  of  one  hundred  words  and 
found  that  the  number  of  common  words  was  very  large. 
Thus  to  man,  394  responded  woman,  99  male,  30  strength, 
44  boy,  30  person,  etc. ;  to  mountain,  246  responded 
high,  184  hill,  73  height,  90  valley;  to  soft,  365  re- 
sponded hard,  53  pillow,  34  easy,  etc.  If  one  will  permit 
the  train  of  ideas  to  wander  uncontrolled  for  five  seconds 
and  then  write  down  the  ideas  that  present  themselves, 
similar  connections  can  be  traced.  The  connections 
have  from  time  immemorial  been  classified  under  four 


THE    LAWS    OF   CENTIL4LLY   AROUSED    SENSATIONS       225 

heads,  —  contiguity,  succession,  similarity,  and  contrast. 
In  our  list  of  words  it  will  be  seen  that  all  the  connec- 
tions given  can  be  traced  to  one  of  these  groups.  Soft 
and  hard,  mountain  and  valley,  man  and  woman,  may 
be  regarded  as  contrasting ;  hill  and  mountain,  soft 
and  easy,  man  and  male,  may  be  regarded  as  similar ; 
soft  and  pillow,  high  and  mountain,  man  and  strength, 
as  connected  through  verbal  succession  or  by  contiguity 
of  the  objects. 

The  Nervous  Basis  of  Association.  —  It  should  be 
noted  that  this  is  always  a  classification  of  the  con- 
nections after  they  have  been  made,  is  made  after 
rather  than  before  the  fact,  is  a  classification  of  the 
relation  the  ideas  hold  to  each  other,  rather  than  a 
statement  of  the  causes  of  recall.  Even  so  far  as  it 
holds,  it  is  not  altogether  unambiguous.  Mountain 
and  valley  are  contiguous  as  well  as  contrasting,  man 
and  woman,  as  all  contrasting  things  must  be,  are  in 
some  degree  similar ;  they  also  are  frequently  found 
together  and  the  words  have  been  repeated  in  succes- 
sion. 

For  the  real  cause  of  arousal,  we  must  turn  again 
to  the  neurones  that  are  involved  in  the  activity.  They 
can  be  connected  in  only  one  way,  by  the  opening  of  the 
synapse  between  the  nervous  elements  involved.  The 
cause  of  the  permeabiHty  of  the  synapses  may  be  made 
the  correlate  of  either  contiguity  or  of  succession.  The 
former  corresponds  directly  to  the  law  of  habit,  — two 
elements  active  together  tend  to  act  together  from  that 
time  on.  Succession  has  practically  the  same  explana- 
tion.    The   second   neurone   begins   to   act  before   the 

Q 


226  FUNDAMENTALS    OF   PSYCHOLOGY 

first  ceases  its  activity,  and  so  the  two  actions  of  the 
neurones  are  simultaneous.  If  similarity  is  to  be  ex- 
plained in  physiological  terms,  it  must  be  reduced  to 
partial  identity.  What  one  calls  an  idea  is  always  com- 
plex and  may  be  pictured  as  corresponding  to  the  action 
of  a  number  of  neurones.  In  what  is  classified  as  asso- 
ciation by  similarity,  a  mass  of  neurones  corresponding 
to  the  first  idea  are  active,  and  as  time  goes  on  parts 
of  the  group  cease  to  be  active,  —  only  one  group  of 
those  corresponding  to  the  part  of  the  idea  most  attended 
to  at  the  moment  persists  in  its  activity,  and  from  this, 
new  neurones  that  correspond  to  the  elements  of  the 
second  idea  are  excited  by  virtue  of  their  previous  con- 
nections with  the  persisting  portions  of  the  first.  On  the 
side  of  consciousness,  many  ideas  in  the  popular  use 
of  the  term  are  complexes  of  experiences,  complexes 
of  sensations  ;  probably  also  the  action  of  many  different 
neurones  is  involved  in  their  appearance.  In  the  recall 
of  any  complex  idea,  these  different  elements  probably 
enter  into  many  different  combinations,  and  the  effective 
connections  are  between  the  elements,  not  between  the 
larger  masses.  Thus  when  an  idea  recalls  another 
similar  one,  the  similarity  is  due  to  some  common  ele- 
ment, and  this  common  element  may  be  regarded  as 
persisting  from  one  idea  to  the  other.  In  one  idea  all 
disappears  but  the  elements  that  are  common ;  these 
persist  and  gather  about  them  by  association  the  other 
elements  which  with  them  may  be  regarded  as  constitut- 
ing the  new  idea.  When  the  ideas  are  classified  after- 
wards, they  are  said  to  be  similar  and  that  the  association 
is  one  of  similarity,  but  the  effective  forces  have  been  the 


THE    LAWS    OF    CEXTIL\LLY   AROUSED    SENSATIONS        227 

waning  of  certain  elements  of  the  first  and  the  excita- 
tion of  others  by  those  remaining.  Association  by  simi- 
larity is  really  through  partial  identity,  and  the  identical 
element  furnishes  the  bond  of  connection. 

Not  only  must  we  limit  the  application  of  the  doctrine 
of  associations  by  the  assertion  that  it  is  the  neurones 
at  the  basis  of  the  elements  of  ideas  that  are  associated 
rather  than  the  ideas  themselves,  but  we  must  also 
recognize  that  associations  give  only  the  possibihty 
of  recall,  and  that  selection  must  be  made  between  the 
possibilities  by  more  remote  factors.  Most  neurones 
or  sensory  elements  have  been  connected  at  different 
times  with  several  other  elements,  and  may  be  regarded 
as  having  a  tendency,  whenever  any  one  is  aroused  in 
any  way,  to  rearouse  each  of  the  others  ^^^th  which  it 
has  been  connected.  Which  of  the  possible  elements 
shall  be  aroused  is  determined  by  the  same  elements 
that  control  attention.  A  discussion  of  these  may  be 
postponed  to  the  next  chapter.  For  the  present  we 
may  say  that  the  return  of  an  experience  or  the  renewal 
of  an  excitation  of  a  group  of  neurones  depends  in  some 
degree  upon  the  continued  activity  (perseveration)  of  the 
elements  in  question,  an  activity  that  lasts  for  a  relatively 
short  time,  but  for  the  most  part  depends  upon  the 
fact  that  when  any  two  groups  of  nerve  cells  have  been 
active  together  at  any  time  and  one  is  reexcited,  that  ex- 
citation tends  to  rearouse  its  earlier  associates. 

The  Qualities  of  Centrally  Aroused  Sensations.  — 
These  mem^ory  processes  may  be  studied,  not  merely 
to  determine  the  ways  in  which  they  are  retained  and 
the  laws  of  their  revival,  but  also  mth  reference  to  the 


228  FUNDAMENTALS   OF   PSYCHOLOGY 

actual  content  that  they  offer.  One  may  study  the 
materials  of  the  remembered  impressions  just  as  one 
may  study  the  qualities  that  are  derived  from  the  ex- 
ternal senses  to  determine  the  elements  that  make 
them  up  or,  more  profitably,  to  compare  them  with  the 
quaHties  of  the  immediate  sensations. 

Most  untrained  individuals  do  not  notice  the  content 
of  their  minds  as  they  recall ;  they  are  content  to  know 
that  they  recall  an  object  and  can  describe  it.  Others 
who  have  had  training  in  introspection  find  that  they 
do  not  have  it ;  they  have  no  definite  mental  content 
when  they  recall  an  object  but  have  merely  the  certainty 
that  they  have  seen  it  before.  Our  present  problem 
is  to  determine  what  is  in  mind  when  the  object  is  re- 
called. If  one  is  attempting  to  recall  a  desert  or  a  moun- 
tain landscape  seen  years  ago,  e.g.,  one  may  either  repeat 
words  that  have  been  associated  with  the  experience 
without  any  definite  picture  of  the  landscape,  one  may 
have  fleeting  bits  of  yellow  sand  or  snow-covered  peaks 
with  many  vacant  areas  or  dark  gray  regions  with 
no  definite  pictures,  or  one  may  have  a  clear  and  dis- 
tinct picture  from  which  one  may  paint  or  describe 
many  if  not  all  of  the  details.  Our  question  at  present 
is  how  these  images  differ  from  individual  to  individual 
and  how  they  resemble,  and  how  they  differ  from,  actual 
sensations. 

Two  methods  of  investigation  have  been  applied  to 

the  solution  of  this  problem.     The  first  of  these  was  used 

by  Kiilpe  ^  in  an  experiment  to  determine  how  one  might 

distinguish  faint  sensations  from  imagined  or  remem- 

1  Kiilpe,  Philosophische  Studien,  vol.  19,  pp.  508-556. 


THE  LAWS  OF  CENTRALLY  AROUSED  SENSATIONS   229 

bered  experiences.  Faint  sensations  were  chosen  be- 
cause memories  are  generally  believed  to  be  fainter 
than  sensations.  Investigators  were  placed  in  a  dark 
room  where  faint  lights  of  different  colors  could  be  thrown 
upon  the  wall.  At  a  given  signal,  the  observers  were 
asked  to  say  whether  a  Hght  was  seen  and  then,  if  it  were 
seen,  to  say  whether  it  was  objective  or  merely  imagined. 
At  times  a  Hght  was  really  shown,  at  others  not.  In 
most  cases  at  the  signal  the  observers  either  saw  or 
imagined  a  color.  After  the  report  had  been  given, 
an  attempt  was  made  to  determine  what  differences 
were  used  as  a  basis  of  deciding  whether  the  image  was 
objective  or  subjective.  In  this  observers  varied.  All 
agreed  that  there  was  a  constant  difference  in  quaHty, 
the  subjective  processes  were  more  transparent,  were 
net-Hke  or  clouded.  The  objective  seemed  brighter, 
they  entered  and  left  consciousness  suddenly  and  as 
wholes,  had  a  more  definite  form,  were  clearer,  and 
were  given  a  more  definite  position  in  space.  They 
were  distinguished  also  by  the  more  active  tests,  —  that 
objective  colors  left  an  after-image,  were  stationary  when 
the  eyes  moved,  and  vanished  on  closing  the  eyes,  —  while 
the  reverse  held  in  each  particular  for  the  subjective 
processes.  In  addition  there  were  indi\ddual  peculiari- 
ties from  man  to  man ;  e.g.,  greater  duration  was  given 
by  one  as  characteristic  of  sensation  and  by  another 
as  characteristic  of  the  image.  The  results  of  this 
investigation  indicate  that  there  are  a  few  characteris- 
tically different  qualities  that  attach  to  the  centrally 
aroused  processes  and  serve  to  distinguish  them  from  the 
more  objective  experiences. 


230  FUNDAMENTALS    OF   PSYCHOLOGY 

The  Projection  of  the  Memory  Image.  —  Another  in- 
vestigation gives  approximately  the  same  results  by  a 
method  even  more  striking.  Miss  Martin  ^  found  that 
it  was  possible  after  a  little  practice  to  project  a  memory 
image  outward  into  space,  where  it  might  be  more  readily 
compared  with  sensations.  The  different  location  of 
images  and  sensations  serves  in  our  ordinary  experience 
as  one  criterion  of  distinguishing  them.  We  project 
sensations  where  the  object  is  assumed  to  be  in  the  out- 
side world,  wliile  the  memory  or  imagination  either  is 
given  an  indefinite  place,  is  projected  backward  within 
the  head,  or  possibly  referred  to  the  place  where  it 
actually  is,  but  usually  not  out  upon  the  surface  that  is 
actually  presented  to  the  eyes.  Miss  Martin's  observers 
found  it  possible  to  bring  the  image  and  the  object  side 
by  side.  When  the  difference  in  projection  that  ordi- 
narily exists  between  images  and  perceptions  had  thus 
been  removed,  it  was  found  that  there  were  still  char- 
acteristic differences  between  the  two  in  their  coloring, 
in  definiteness  of  contours,  in  clearness,  intensity,  and 
stability.  The  sensations  had  the  advantage  in  each  of 
these  respects.  One  other  characteristic  is  the  rela- 
tion to  the  movements  of  the  eyes.  While  in  these 
experiments  the  images  did  not  always  move  with  the 
eyes,  there  was  always  a  tendency  to  movement  when 
the  eyes  moved  that  could  be  avoided  only  by  consider- 
able strain.  All  of  these  criteria  for  distinguishing 
between  the  two  agree  with  those  indicated  by  Kulpe's 
investigation.     One    other    presents    itself    for    certain 

*  Martin,  Die  Projektionsmethodc  und  die  Lokalisation  visueller  und 
andercr  Vorstellungsbildcr. 


THE   LAWS   OF   CENTRALLY   AROUSED    SENSATIONS        23 1 

observers,  —  that  is  the  tendency  to  see  the  images 
in  front  of  the  background  of  sensory  objects  which 
^may  be  present.  The  background  may  be  seen  through 
them  as  through  a  veil.  In  general  it  is  noticed  that 
sensory  impressions  interfere  wdth  the  perception  of 
other  objects,  while  images  do  not  thus  interfere. 

Individuals  who  possess  definite  images,  then,  have 
also  characteristic  means  of  distinguishing  them  from 
the  sensations,  —  they  show  differences  from  the  sen- 
sory experiences  constant  enough  to  prevent  one  from 
being  mistaken  for  the  other.  Indi\iduals  may  not 
notice  the  characteristics  that  serve  to  distinguish 
images  from  sensations.  In  fact,  few  do  until  they  have 
been  called  to  their  attention,  but  the  dift'erences  serve 
to  ascribe  the  process  to  the  world  of  things  if  of  one 
character,  or  to  memory  or  imagination  if  of  another 
character.  In  addition  to  these  differences  in  the  men- 
tal content,  the  connections  in  which  the  experiences 
present  themselves  also  play  a  part  in  determining 
whether  an  experience  is  objective  or  subjective.  If 
the  object  or  event  follows  naturally  upon  other  events 
that  are  recognized  as  objective,  if  the  sound  of  steps 
is  heard  outside,  the  bell  rings,  a  servant  answers  and 
a  moment  later  a  friend  enters  the  room,  there  is  no 
question  of  the  objectix-ity  of  the  experience.  If,  on 
the  other  hand,  a  letter  in  a  famiHar  handwTiting  is 
seen  and  then  an  image  of  the  friend  who  wrote  the 
letter  appears,  there  is  no  doubt  that  the  image  is  sub- 
jective. One  event  fits  into  the  objective  setting,  the 
other  into  the  memory  picture,  and  in  consequence  the 
one  is  assigned  to  the  one  group,  the  other  to  the  other. 


232  FUNDAMENTALS   OF   PSYCHOLOGY 

This  placing  of  the  mental  process  in  terms  of  ante- 
cedent events  and  the  setting  is  undoubtedly  the  most 
important  of  the  factors  that  lead  us  to  discriminate 
between  the  objective  and  the  subjective.  Again  this 
operation  is  not  noticed  for  itself.  One  knows  at  once 
that  one  sees  an  object  in  the  one  case  and  that  one 
merely  remembers  it  in  the  other.  The  method  of 
remembering  is  no  more  noticed  than  is  the  method  of 
perceiving. 

One  may  in  a  sense  and  for  most  individuals  parallel 
the  sensations  which  are  regarded  as  constituting  the 
raw  material  of  our  external  experiences  by  a  series  of 
images  or  centrally  aroused  sensations  which  constitute 
the  materials  out  of  which  the  things  that  appear  in 
memory,  imagination,  and  reason  are  composed,  '  the 
stuff  of  which  dreams  are  made.'  These  are  retained 
in  the  central  nervous  system  and  rearoused  by  stimuli 
that  have  been  connected  with  them  in  the  past  and  by 
other  ideas  that  have  been  experienced  with  them.  It 
should  be  noted  that  the  memory  images  are  usually 
not  so  complete  as  the  sense  presentations,  that  even 
the  clearest  of  them  have  large  gaps  due  either  to  im- 
perfect attention  at  the  time  of  perception  or  to  lack  of 
interest  in  that  phase  at  the  moment  of  recall.  Also 
much  of  our  memory  and  thinking  is  not  in  definite 
reproductions  or  constructions  of  the  objects,  but  is 
very  sketchy.  It  is  very  frequently  in  words  or  in  some 
other  symbol  that  represents  or  means  the  thing  rather 
than  constitutes  it.  This  must  be  considered  in  detail 
later  on ;  it  is  mentioned  now  merely  as  indicating  that 
our  inner  mental  life  is  not  to  be  described  completely  in 


THE   LAWS   OF   CEXTR.\LLY   AROUSED    SENSATIONS       233 

terms  of  delxnite  images.  Even  where  centrally  aroused 
sensations  are  most  definite,  the  number  of  quahties 
is  less  than  the  number  that  may  be  found  in  immediate 
sensation.  Of  the  hundreds  of  grays  the  unpractised 
man  cannot  recall  more  than  a  dozen.  Relatively  few 
elements  in  memory  must  be  made  to  do  duty  for  the 
vast  number  of  sensation  qualities. 
//Memory  Types.  —  In  our  discussion  of  the  qualities 
of  the  centrally  aroused  processes,  it  must  be  noticed 
not  only  that  the  quality  of  the  memory  element  is  not 
the  same  as  the  quahty  of  the  thing  represented,  but 
the  way  in  which  anything  is  recalled  differs  greatly 
from  indi\idual  to  indi\'idual.  We  all  think  of  the 
same  things,  but  probably  no  two  of  us  have  in  mind 
exactly  the  same  images  when  we  think  of  the  object. 
The  main  dift'erences  in  representing  objects  and  events 
can  be  most  readily  stated  in  terms  of  the  sense  organ 
or  the  sense  material  that  is  emphasized  or  drawn  upon 
by  the  indi\'idual.  The  students  of  mental  disturbance, 
Charcot  among  the  first,  noticed  that  certain  men  would 
make  predominant  use  of  the  \dsual  memories,  others 
of  the  motor,  others  again  of  the  auditory.  Still  later 
Galton  ^  made  a  careful  examination  of  the  way  a  number 
of  indi\iduals  recalled  the  breakfast  table,  with  the  result 
that  some  were  found  who  would  merely  recall  the  way 
the  dishes  and  the  people  at  the  table  looked,  others 
could  remember  the  sounds  of  words  and  the  rattle  of 
the  utensils,  still  others  could  remember  only  how 
their  own  various  movements  felt  as  they  were  made. 
More  rare  were  the  indi\iduals  who  could  remember 
^  Gallon,  Inquiries  into  Human  Faculties. 


234  FUNDAMENTALS   OF   PSYCHOLOGY 

the  odors  and  tastes  of  the  food,  and  these  memories 
were  usually  indistinct  and  subordinate.  Galton  also 
distinguished  the  verbal  type,  individuals  who  recalled 
everything  in  words,  either  as  words  seen,  or  words 
heard,  or  words  as  they  would  be  felt  in  the  vocal  organs 
at  the  time  they  were  uttered.  In  older  indi\iduals, 
particularly  men  of  science  and  others  who  indulged 
much  in  abstract  thought,  the  verbal  tended  to  predomi- 
nate over  the  more  concrete  imagery. 

Galton  or  certain  of  his  expositors  leave  the  impres- 
sion that  an  individual  is  likely  to  have  one  type  to  the 
exclusion  or  at  the  expense  of  all  others.  Certain  of 
the  later  writers  have  still  more  exaggerated  this  asser- 
tion of  the  mutual  exclusiveness  of  types.  Strieker,  for 
instance,  has  argued  that  every  one  must  be  of  the  motor 
type,  and  further  that  the  recall  consists  in  nothing  more 
than  the  reinstatement,  in  some  slight  degree,  of  the 
movements  made  on  a  large  scale  at  the  time  of  the 
original  experience.  He  challenges  any  one  to  think  the 
sound  of  0  with  closed  lips,  and  regards  failure  to  do  so 
as  proof  of  his  contention  that  all  thinking  is  in  terms 
of  a  reinstatement  of  some  movement.  Most  recent 
investigators,  however,  incline  to  the  view  that  while 
imagery  is  much  more  restricted  than  sensation,  that 
most  individuals  have  more  than  one  type,  many  two 
or  more,  in  approximately  the  same  degree.  These 
individuals  will  use  the  type  of  imagery  most  suited  to 
the  problem  in  hand.  If,  e.g.,  one  both  paints  and 
composes  music,  one  would  plan  a  picture  in  visual 
images  and  compose  in  auditory  terms.  While  one 
or  more  types  may  be  lacldng  in  most  individuals,  and 


TIIE   LAWS    OF   CENTRALLY   AROUSED    SENSATIONS        235 

one  or  more  be  preferred,  the  sharp  classification  into 
\'isual,  auditory,  etc.,  seems  rather  too  rigid  to  harmonize 
■uith  the  facts.  Miss  Fernald  finds  three  main  types,  — 
one  in  which  the  difi'erent  images  are  used  with  approxi- 
mately equal  readiness,  one  predominantly  \isual  and 
motor,  and  a  third  auditory  and  motor. 

Much  remains  to  be  done  on  many  phases  of  the  study, 
particularly  from  the  statistical  side.  At  present  the 
data  as  to  the  number  of  each  t}pe,  and  the  degree  of 
dift'erence  between  the  types,  are  deficient  in  very  many 
respects.  We  do  not  know  on  any  very  trustworthy 
experimental  basis  the  relative  proportions  of  the  dif- 
ferent t^pes,  and  their  distribution  with  reference  to  pro- 
fessions or  general  capacities.  Lacking  this,  it  is  also 
not  possible  to  reach  any  conclusion  as  to  how  the  dif- 
ferences are  brought  about.  Evidence  may  be  adduced 
by  a  few  cases  in  favor  of  an  hereditary  predisposition. 
Dodge,  who  is  almost  altogether  without  auditory  im- 
agery, reports  that  his  parents  had  the  same  lack.  The 
inheritance  of  musical  ability,  which  in  all  probability 
depends  upon  the  possession  of  auditory  imagery,  may 
also  be  cited  as  evidence  of  an  hereditary  tendency. 
On  the  other  side,  training  has  been  shown  in  several 
indi\ddual  cases  to  have  exerted  an  influence  in  chang- 
ing the  memory  type.  Particularly  with  school  children, 
it  is  found  that  they  can  be  trained  to  considerable 
facility  in  t>pes  of  imagination  in  which  they  possess 
no  natural  skill.  Even  in  adults  long  practice  gives 
results  in  the  development  of  new  forms  of  imagery. 
A  student  who  cannot  spell  because  he  cannot  see  the 
words  in  liis  mind's  eye  can  by  repeated  effort   bring 


236  FUNDAMENTALS   OF   PSYCHOLOGY 

himseK  to  visualize  the  words,  with  some  degree  of  im- 
provement on  the  practical  side.  It  does  not  follow 
that  spelling  is  absolutely  dependent  upon  the  possession 
of  the  visual  type.  It  seems,  then,  that  both  heredity 
and  training  may  play  a  part  in  determining  the  mental 
type,  —  certainly  training  may  change  what  is  given 
by  heredity. 

Synaesthesia.  —  A  curious  occasional  phenomenon  is 
found  in  the  close  connection  in  certain  individuals 
between  objects  or  sensations  of  different  senses.  It  is 
most  frequent  in  the  association  of  sounds  with  colors, 
—  a  sound  tends  to  arouse  at  once  certain  colors  that 
are  characteristic  of  the  sound.  Numerous  cases  have 
been  recorded  in  which  letters  have  colors  attached :  a 
is  pink,  0  green,  etc.,  and  words  either  will  have  a  color 
of  their  own,  or  will  take  on  the  color  of  the  letters  that 
make  them  up.  Several  cases  have  been  reported,  too, 
in  which  musicians  will  have  colors  aroused  by  certain 
tones  or  tone  combinations,  and  these  may  seem  to 
be  essential  components  of  the  tone  effects.  Thus 
Myers  reports  that  Scriabin,  the  Russian  composer,  had 
a  different  color  for  the  different  keys.  The  major 
keys  of  C,  D,  B,  and  F#  have  the  colors  of  red,  orange- 
yellow,  blue,  and  violet,  respectively,  and  the  effects 
are  so  strong  that  he  desired  to  have  his  compositions 
rendered  to  the  accompaniment  of  colored  lights  that 
should  flood  the  hall  from  concealed  lamps.  In  another 
striking  case  odors  were  associated  with  colors ;  in  fact, 
were  often  only  perceived  through  their  color  associations. 

Two  theories  have  been  held  to  account  for  the  phe- 
nomenon:  one  that  the  connections  have  been  made 


THE  LAWS  OF  CENTRALLY  AROUSED  SENSATIONS   237 

through  association,  the  other  that  it  is  fundamental 
and  perhaps  due  to  the  fact  that  there  is  some  common 
feeling  or  other  element  which  serves  to  connect  the  two 
sensory  components.  The  second  theory  if  true  must 
admit  that  indi\dduals  who  possess  this  idiosyncrasy 
seldom  agree  as  to  the  colors  that  shall  be  associated 
■^vith  a  particular  tone.  Each  person  who  has  the  idio- 
s}Ticrasy  feels  that  it  is  universal  and  necessary.  The 
association  theory  is  as  yet  equally  unproven,  although 
a  few  characteristic  peculiarities  suggest  that  colors 
may  be  taken  from  old  habits.  Thus  in  three  sisters 
whom  I  investigated,  one  of  the  few  correspondences 
was  thaty  was  said  to  have  a  gritty  bro^vn  color  to  all 
three,  an  ob\^ous  connection  ^\ithyjug.  How  far  heredity 
plays  a  part,  how  far  there  may  be  more  fundamental 
common  characteristics  between  the  sensations  con- 
nected, and  how  far  the  phenomenon  may  be  merely  the 
result  of  early  associations  is  still  largely  a  matter  of 
conjecture. 

In  brief,  the  qualities  of  centrally  excited  processes 
are  the  same  as  the  qualities  of  sensations,  a  little 
less  numerous,  ^vith  not  quite  the  same  distinctness, 
but  with  no  new  qualities  added.  These  impressions 
are  recalled  through  the  laws  of  association  not  so  very 
different  from  the  laws  of  habit,  and  are  woven  together 
in  new  patterns  to  give  features  of  remembered  events 
that  suit  the  purpose  of  the  moment,  or  to  make  new 
constructions  of  imagination  or  reason.  As  is  to  be 
seen  in  the  next  chapter,  these  constructions  are  sub- 
ordinate to  more  general  controls  in  the  same  degree 
and  by  the  same  laws  as  sensations. 


CHAPTER  VII 

ATTENTION  AND    SELECTION 

No  study  of  the  mental  life  of  man  can  be  content 
with  an  enumeration  of  the  sensations,  peripherally  and 
centrally  aroused,  and  with  the  laws  of  association. 
These  may  be  said  to  give  the  materials  of  mind,  but 
to  understand  either  action  or  consciousness  much  more 
is  required.  Everywhere  in  mental  life  we  lind  signs  of 
spontaneity,  indications  that  the  effects  of  stimuli  and 
the  laws  of  association  do  not  alone  sufhce  to  explain  all. 
The  individual  selects  from  among  the  stimuli,  seems 
to  increase  the  effect  of  one  at  the  expense  of  the  others. 
On  the  active  side  one  stimulus  is  more  likely  to  produce 
a  response  than  the  others ;  in  consciousness  it  becomes 
clearer,  and  lasts  longer.  These  effects  are  ascribed  to 
attention.  Attention  is  not  a  faculty ;  it  is  merely  a  name 
that  has  been  given  to  the  fact  that  there  is  selection, 
that  the  selected  stimulus  becomes  more  effective,  more 
prominent  in  consciousness,  and  more  likely  to  cause, 
movements,  and  also  at  times  it  has  been  given  to  the 
conditions  of  these  changes.  1 

The  fact  of  attention  is  apparent  to  all  and  at  all  times. 
As  one  looks  out  over  a  landscape,  one  feature  after  an- 
other is  noticed ;  as  one  sits  at  the  study  table  working, 
the  noise  of  the  street,  and  memories  of  all  kinds,  will 

238 


ATTENTION  AND   SELECTION  239 

from  time  to  time  intrude  themselves  and  crowd  out  the 
material  that  is  coming  in  from  the  page  of  the  book, 
even  if  the  eyes  still  wander  along  the  lines  of  print  and 
all  the  other  physical  conditions  of  reading  are  un- 
changed. In  both  cases  the  mental  content  varies  be- 
cause of  changes  within  rather  than  without.  A  slight 
observation  of  the  course  of  mental  processes  shows  that 
most  of  the  changes  are  subjective  rather  than  merely 
physical.  We  are  conscious  at  any  time  of  only  a  fraction 
of  the  things  that  might  be  observed.  Many  sensory 
experiences  pass  unnoticed  unless  we  look  for  them  partic- 
ularly. The  vast  majority  of  objects  presenting  them- 
selves to  the  eyes  are  not  seen,  and  many  of  the  sounds 
that  fall  upon  the  ear  are  not  heard.  We  select  only  the 
few  that  appeal  to  us  at  the  moment. 

Does  Attention  Increase  the  Intensity  of  Sensation  ?  — 
To  begin  with  the  change  in  content  with  attention,  we 
must  ask  what  this  change  is.  The  answer  is  to  be  found 
in  the  observation  of  one's  own  state  as  one  attends, 
rather  than  in  a  verbal  description.  Certain  it  is  that  the 
object  or  event  attended  to  becomes  in  every  way  more 
important  for  consciousness ;  it  stands  out  above  the 
others  at  the  moment,  is  also  more  likely  to  be  remem- 
bered and  to  start  new  trains  of  thought.  The  character 
of  the  change  can  be  given  only  by  comparing  it  with 
other  known  changes  and  indicating  the  similarities  and 
differences  between  them.  In  many  respects  it  is  like 
an  increase  in  intensity.  Increase  in  the  intensity  of  a 
physical  stimulus  also  makes  it  more  likely  to  enter  con- 
sciousness, increases  the  probability  of  recall,  and  quickens 
reaction  to  it.     That  they  are  not  identical  is  evident 


240  FUNDAMENTALS   OF  PSYCHOLOGY 

from  the  fact  that  we  never  mistake  one  for  another. 
On  the  other  hand,  it  is  certain  that  the  two  changes 
have  much  the  same  practical  effects ;  both  attention 
and  intensity  make  the  experience  more  important  for 
consciousness.  Attention  also  produces  an  increased 
clearness  of  outline.  In  this  respect  it  has  an  effect 
similar  to  that  due  to  increased  closeness  of  the  nerve 
terminations.  \ 

Consciousness  as  a  whole  has  been  likened  by  Wunit 
to  the  field  of  vision.  There  is  a  point  of  clearest  vision 
in  the  centre  where  the  cones  are  very  close  together, 
and  a  gradually  decreasing  clearness  as  one  passes  out- 
ward to  the  circumference.  The  point  of  maximum  at- 
tention corresponds  to  the  fovea  in  the  field  of  vision^ 
the  other  regions  of  consciousness  to  the  periphery. 
Attention  may  wander  over  the  field  of  consciousness  ' 
in  much  the  same  way  that  the  eye  wanders  over  the 
field  of  vision.  The  common  characteristic  of  foveal 
vision  and  attention  is  the  increased  clearness  that 
comes  in  both  cases.  As  a  result,  contours  and  differ- 
ences in  intensity  between  parts  are  better  discrimi- 
nated. Temporal  effects  of  attending  to  a  sensation  have 
been  noted  in  hastening  its  entrance  and  in  keeping  it  a  m 
little  longer  in  consciousness.  All  these  differences  would 
increase  the  importance  of  the  impression  attended  to 
as  compared  with  one  that  is  not  attended  to. 

The  Distribution  of  Clearness.  —  Much  discussion  has 
arisen  in  the  last  few  years  among  the  people  who  would  . 
make  clearness  the  primary  characteristic  of  the  atten- 
tive consciousness,  as  to  the  way  in  which  clearness  is 
distributed  over  the  field  of  consciousness.     Titchener 


ATTENTION   AND   SELECTION  24I 

regards  clearness  as  one  of  the  fundamental  attributes 
of  consciousness,  on  the  same  level  with  quaHty  or  inten- 
sity. He  first  asserted  that  there  are  at  any  moment 
in  consciousness  but  two  degrees  of  clearness,  — the  centre 
upon  which  attention  is  fixed  and  the  hazy  background. 
This  first  statement  was  softened  in  large  measure,  how- 
ever, by  the  admission  that  there  might  be  dift'erences  in 
clearness  in  both  upper  and  lower  levels,  separated  by  a 
marked  break  in  the  degree  of  clearness  between  the  two 
levels.  Under  the  criticism  of  Wirth,  who  asserted  that 
consciousness  grades  oft'  gradually  from  the  clearest  point 
to  the  most  obscure,  Titchener  renewed  his  investigation 
of  the  question,  and  found  that  there  was  a  difference 
between  individuals  in  this  respect,  that  certain  people 
belonged  to  the  two-level  t>'pe,  others  had  a  number  of 
dift'erent  levels  or  even  approached  the  gradual  passage 
from  maximum  to  minimum  clearness  that  Wundt  had 
described  as  the  universal  t}^e. 

Attention  as  Selection.  —  The  process  of  selection 
requires  less  description  although  in  its  ramifications  it 
probably  takes  more  different  forms  and  is  more  impor- 
tant in  its  eft'ects  upon  consciousness.  In  part,  selection 
is. effected  by  increasing  the  clearness  of  the  content, 
an  element  obscure  at  one  moment  becomes  clear  at  the 
next ;  in  part,,  the  process  selected  rises  from  complete 
obscurity  to  a  dominating  place  in  consciousness,  a  possi- 
ble content  is  made  actual  at  one  stroke.  We  are  con- 
cerned with  it  primarily  in  connection  with  the  admission 
of  certain  stimuli,  —  with  the  fact  that,  with  attention,  a 
stimulus  that  has  been  present  but  ineffective  suddenly 
rises  to  a  prominent  place.     In  later  discussions  it  will  be 


242  FUNDAMENTALS   OF  PSYCHOLOGY 

seen  that  the  fact  of  selection  is  of  fundamental  impor- 
tance ;  that  we  select  not  merely  stimuli,  but  that  we  select 
ideas  from  among  those  made  possible  by  association,  and 
through  ideas  we  reach  decisions  and  select  acts.  It 
will  be  found,  too,  that  many  of  the  same  principles,  many 
of  the  same  conditions,  are  involved  in  the  selection  of 
these  higher  or  more  complicated  processes  that  are  in- 
volved in  the  simpler  operations  we  are  dealing  with  here. 
Motor  Concomitants  of  Attention.  —  If  we  turn  from 
function  to  subordinate  features  of  attention,  we  find  that 
a  characteristic  quality  is  given  the  experience  of  attend- 
ing, both  for  the  one  attending  and  the  observer,  by  its 
accompanying  movements.  These  are  of  varied  sorts 
and  degrees.  Most  important  in  practice  are  the  actions 
involved  in  the  accommodation  of  the  sense  organs.  As 
one  attends,  the  organ  adjusts  itself  to  give  the  best 
possible  conditions  for  observation.  The  eye  at  once 
turns  so  that  the  object  falls  upon  the  fovea,  the  lens 
without  further  thought  is  given  the  right  curvature,  the 
eye  is  in  consequence  focussed  for  the  distance  of  the 
object,  and  the  two  eyes  are  converged  to  permit  both 
to  see  it  with  the  fovea.  Each  of  these  adjustments  is 
made  without  specific  intention  and  usually  without 
knowledge  that  they  have  been  or  are  being  made.  One 
cannot  adjust  the  lens,  contract  the  ciliary  muscle,  by 
direct  impulse.  The  only  way  to  move  the  muscle  is 
by  changing  attention.  If  one  attends  to  a  distant  ob- 
ject, the  muscle  relaxes ;  if  one  attends  to  a  near  object 
closely,  it  contracts,  but  this  is  the  only  way  that  it  can 
be  made  to  act.  The  same  statement  holds  in  less  degree 
of  turning  and  converging  the  eyes.     The  movement 


ATTENTION  AND   SELECTION  243 

follows  at  once  upon  attention  and  is  always  a  result  of 
attending.  In  the  other  senses,  the  adjustments  of  the 
sense  organs  are  less  striking,  although  still  present. 
The  head  is  turned  toward  the  source  of  sound  to  increase 
the  certainty  of  receiving  the  tones.  This  is  particularly 
noticeable  if  one  ear  be  defective.  The  head  will  then  be 
turned  to  one  side  w^hen  listening  to  receive  as  much  as 
possible  of  what  is  being  said.  The  muscles  in  the  middle 
ear  probably  have  a  protective  function  only,  and  play 
little  part  in  attentive  listening.  When  one  is  asked  if 
one  notices  smoke,  sniffing  follows  automatically  to  bring 
as  much  air  as  possible  to  and  through  the  nostrils.  Simi- 
larly, when  a  cook  passes  critical  judgment  upon  a  product 
of  his  art,  the  substance  is  pressed  more  closely  against 
the  tongue  by  bringing  the  tongue  against  the  roof  of 
the  mouth.  In  feeling  a  surface  the  hands  are  kept  in 
motion  that  the  slighter  irregularities  may  be  noticed. 
In  the  blind  this  frequently  develops  into  a  series  of  slight 
movements  of  the  finger  tips  made  automatically  and 
almost  unconsciously.  Comparing  weights  calls  out 
similar  lifting  movements  of  the  whole  arm.  Each  sense, 
then,  has  a  series  of  accommodatory  movements  that 
make  the  sensation  more  adequate  and  complete,  move- 
ments that  come  without  thought,  are  an  immediate 
outcome  of  attending,  of  the  desire  to  know  more  about 
the  object  in  which  one  is  interested. 

Mimetic  Movements.  —  Another  characteristic  group 
of  movements  is  carried  out  by  the  voluntary  muscles 
of  all  parts  of  the  body,  which  depend  for  their  char- 
acter upon  the  nature  of  the  thing  attended  to.  Every 
movement  that  is  absorbing  or  that  is  watched  atten- 


244  FUNDAMENTALS   OF  PSYCHOLOGY 

lively  tends  to  induce  or  be  accompanied  by  similar 
movements  on  the  part  of  the  onlooker.  Thus  if  one  is 
watching  an  athletic  contest  closely,  it  is  probable  that 
one  will  make  slight  movements  in  imitation  of  the  con- 
testants. This  tendency  to  act  out  ideas  explains  many 
of  the  cases  of  mind  reading  and  similar  processes  that 
approach  the  occult.  Slight  movements  made  without 
the  knowledge  or  intention  of  the  one  and  interpreted 
without  the  knowledge  of  the  other  serve  as  a  basis  for 
the  communication.  The  capacity  for  interpreting  these 
slight  unconscious  movements  is  found  in  animals  as  well 
as  in  man.  The  feats  of  "  Kluge  Hans  "  and  the  Elber- 
feld  horses  who  seemed  to  do  sums  and  perform  other 
wonders  were  found  on  closer  examination  to  depend 
in  part  upon  noticing  signals  from  the  trainers  which 
were  given  without  the  knowledge  of  the  trainers.  Thus 
a  horse,  when  given  a  sum  on  the  board,  would  begin 
to  stamp  and  continue  the  movements  until  the  trainer 
indicated  his  satisfaction  by  some  slight  movement. 
These  movements  of  the  muscles  of  the  face  and  of  the 
bodily  attitude  constitute  a  large  element  in  the  ap- 
preciation of  the  mental  attitude  of  a  companion. 

Diffuse  Motor  Discharges.  —  Still  another  large  group 
of  movements  of  the  voluntary  muscles  accompanying 
attention  is  constituted  by  a  contraction  of  most  of  the 
muscles  of  the  body,  due  to  a  general  discharge  of  im- 
pulses, a  sort  of  overflow  of  motor  excitations.  As  one 
attends  strongly  to  any  object  one  becomes  tense,  the 
brow  wrinkles,  the  teeth  are  set,  the  fists  may  be  clenched. 
The  degree  of  tension  increases  with  the  degree  of  atten- 
tion.    One  uses  the  feelings  of  strain  subjectively  as  a 


ATTENTION   AND    SELECTION  245 

measure  of  the  amount  of  attention,  and  one  also  regards 
the  amount  of  contraction  as  a  measure  of  the  attention 
of  another.  It  is  not  necessarily  true  that  the  efficiency 
of  attention  is  measured  accurately  by  the  amount  of 
contraction  or  of  the  resultant  feeling  of  strain.  These 
strains  seem  to  be  more  pronounced  when  the  resistance 
to  be  overcome  is  great,  rather  than  when  one  is  attend- 
ing to  the  best  advantage.  But  it  is  taken  by  the  individ- 
ual himself  as  an  indication  of  the  effort  that  he  is  exert- 
ing in  attention,  or  of  the  eflort  that  he  is  exerting  in  any 
field.  Closely  connected  with  these  general  contractions 
and  accompanying  marked  attention  is  the  inhibition  of 
all  movements.  Some  indi^dduals  must  stop  any  move- 
ment they  may  be  engaged  in  when  they  begin  to  attend, 
and  in  all  there  is  checking  of  movements  when  attention 
becomes  close.  It  can  be  noticed  most  clearly  in  an 
audience.  When  inattentive,  there  is  always  a  sound 
made  by  the  rustle  of  garments,  by  other  movements, 
each  in  itself  too  sHght  to  make  a  noticeable  noise,  but 
which  in  the  sum  produce  a  marked  disturbance.  As 
soon  as  the  audience  becomes  attentive,  all  this  stops  and 
silence  ensues.  These  inhibitions  are  of  value  in  listen- 
ing for  faint  sounds,  and  in  many  other  sorts  of  attention 
they  may  increase  the  effectiveness  of  the  sense  in  some 
degree.  In  time  it  has  become  habitual  or  even  an  in- 
stinctive accompaniment  of  all  attending. 

Changes  in  non-voluntary  physiological  processes  also 
are  present.  These  are  perhaps  most  strikingly  seen  in 
the  checking  of  respiration.  As  one  attends,  the  breath- 
ing is  checked.  In  a  short  period  of  profound  attention 
the  breath  will  be  held  and  a  sigh  or  deep  inspiration  will 


246  FUNDAMENTALS   OF  PSYCHOLOGY 

follow  relaxation.  In  longer  periods  the  breathing  first 
becomes  quick  and  shallow ;  in  still  longer  periods  it  is 
slower,  but  also  more  shallow  than  usual.  Similarly, 
there  are  changes  in  the  circulation.  The  heart  beats 
more  quickly,  the  blood  vessels  contract  in  the  periphery 
and  expand  in  the  brain,  the  blood  pressure  rises,  the 
pupils  are  dilated,  tears  are  secreted  which  give  the  bright 
eye  of  interest.  Each  of  these  movements  renders  the 
organism  more  efficient.  Holding  the  breath  removes 
the  noises  of  respiration  that  might  interfere  with  faint 
sounds.  The  quicker  heart  beat  and  increased  circula- 
tion in  the  brain  prepare  better  for  appreciation  of  the 
conditions,  and  for  the  activity  that  may  follow.  At- 
tention, then,  has  widespread  physical  as  well  as  mental 
effects.  Accompanying  increased  appreciation  of  some 
one  sensation  or  stimulus  is  a  widespread  irradiation 
of  impulses  to  the  muscles.  These  serve  to  increase 
bodily  capacity,  are  an  indication  to  an  onlooker  of 
attending  and  of  the  direction  of  attention.  The 
sensations  of  strain  which  come  from  the  contractions 
are  assumed  to  measure  the  degree  of  attention. 
Most  so-called  mental  tension  is  physical,  due  to  these 
muscular  contractions. 

The  Range  of  Attention.  —  One  of  the  concrete  prob- 
lems that  has  been  frequently  discussed  and  most  often 
measured  in  connection  with  attention  is  its  range,  the 
number  of  things  that  may  be  perceived  at  once.  The 
experiments  have  been  carried  out  by  making  very  brief 
exposures  of  a  number  of  objects,  and  asking  an  ob- 
server how  many  have  been  seen.  The  exposure  is 
limited  to  a  fifth  of  a  second  or  less,  a  time  which  does 


ATTENTION   AND    SELECTION  247 

not  permit  any  change  of  the  attention  or  movement  of 
the  eye.  Results  agree  that  four  or  five  objects  may  be 
seen  at  a  single  exposure.  It  is  interesting  to  note,  too, 
that  the  number  of  objects  that  may  be  seen  is  relatively 
independent  of  the  size  or  complexity  of  the  object.  One 
dot,  a  group  of  three  or  more  that  makes  some  regular 
figure,  a  letter,  or  a  small  word  are  all  seen  with  approxi- 
mately the  same  ease.  In  fact,  a  short  word  is  more 
certain  to  be  recognized  than  a  single  letter.  What 
constitutes  a  single  object  is  fundamentally  that  it  has 
been  used  or  treated  as  a  single  thing,  rather  than  its 
physical  complexity.  The  number  of  auditory  impres- 
sions is  slightly  greater  than  the  visual,  but  they  must 
of  course  be  given  in  succession.  Eight  single  ticks  of 
a  metronome  may  be  appreciated  when  heard  without 
rhythm,  and  when  combined  in  a  rhythm  as  many  as  40, 
five  groups  of  eight  each,  can  be  heard  in  a  single  unit. 
The  experiments  also  make  it  probable  that  the  objects 
are  not  really  seen  all  at  once  but  that  they  are  counted 
after  the  exposure  in  the  immediate  memory  or  memory 
after-image.  Careful  examination  of  the  process  of  at- 
tending to  objects  exposed  for  an  instant  shows  that  the 
real  study  of  the  object  is  made  after  the  exposure. 
Impressions  persist  in  the  memory  after-image  wdth  con- 
siderable vividness  for  some  two  seconds,  long  enough 
to  count  the  five  objects  successively.  One  really,  then, 
attends  to  but  a  single  object  at  a  time,  but  five  succes- 
sive acts  of  attention  can  be  completed  before  the  vivid 
memory  image  disappears. 

Much  the  same  problem  has  been  raised  with  refer- 
ence to  how  many  processes  may  be  carried  on  at  once. 


248  FUNDAMENTALS   OF   PSYCHOLOGY 

Occasionally  one  reads  that  some  man  has  the  capacity 
of  doing  two  or  more  things  at  a  time.  Caesar  was  said 
to  dictate  to  several  secretaries  at  once,  and  similar  tales 
are  told  of  others.  Experiments  have  been  carried  on  to 
test  the  point  and  all  indicate  that  more  than  one  process 
may  be  carried  on  at  one  time,  but  only  provided  one 
is  sufficiently  automatic  to  require  no  attention.  Thus 
it  is  possible  to  write  from  dictation  and  do  mental 
additions  at  the  same  time,  and  the  time  required  for 
doing  both  will  be  less  than  the  sum  of  tlje  times  for  doing 
each  separately.  If  it  is  attempted  to  do  three  things 
simultaneously  or  to  do  two  things  even  one  of  which  has 
not  become  pretty  thoroughly  automatic,  more  time  is 
required  to  carry  them  on  together  than  separately. 
Here  again  it  seems  that  one  can  attend  to  but  one  thing 
at  a  time,  although  it  is  possible  to  start  one  series  of 
activities  and  let  it  go  on  of  itself  while  one  attends  to 
something  else  for  a  time.  Attention  changes  from  one 
to  the  other  just  often  enough  to  keep  the  different  pro- 
cesses going. 

The  Duration  of  Attention.  —  Another  question  of 
similar  character  is  how^  long  one  may  attend  without  a 
break.  This  question  has  been  given  different  answers 
at  different  times,  and  the  answer  depends  in  part  upon 
what  is  meant  by  the  question.  Speaking  roughly,  one 
may  attend  to  the  same  general  subject,  may  read  a  book, 
for  example,  for  an  indefinite  period.  Careful  observa- 
tion of  the  course  of  attention  to  faint  stimuli  shows  that 
there  are  periods  when  they  will  be  appreciated,  other 
times  when  they  cease  to  be  noticed.  Thus  if  one  will 
listen  to  the  ticking  of  a  watch  or  the  faint  tone  of  a 


ATTENTION   AND    SELECTION  249 

telephone  at  a  little  distance,  it  ^\ill  be  noticed  that  the 
sound  will  be  heard  for  an  instant  and  then  will  disap- 
pear, and  these  alternations  will  continue  as  long  as  one 
listens.  Similar  fluctuations  are  present  during  the 
observation  of  faint  \isual  stimuli.  The  explanation 
of  these  fluctuations  has  been  variously  given  as  due  to 
fatigue  in  the  sense  organs,  either  of  the  muscles  or  of 
the  sensory  endings,  to  fatigue  of  the  sensory  regions 
in  the  cortex,  or  to  changes  in  the  blood  supply  to  the 
cortex,  and  even  to  fluctuations  of  mental  energ}' .  The 
explanation  cannot  be  regarded  as  completely  agreed 
upon,  although  considerable  e\'idence  has  been  given  in 
favor  of  all  but  the  last  theory.  WTiat  is  probably  more 
truly  a  fluctuation  of  attention  is  seen  if  one  will  keep  a 
record  of  the  time  that  one  can  fix  upon  some  single, 
simple  object,  a  dot  or  a  single  tone.  It  will  be  seen 
that  the  single  object  will  dominate  consciousness  for 
only  a  second  at  the  most,  then  something  in  the  neigh- 
borhood ^^^ill  crowd  out  the  first,  or  a  memory  of  some 
event  of  the  past  ^^dll  intrude  to  exclude  it.  Between 
each  of  the  other  events  attention  will  go  back  to  the  dot. 
The  observer  will  be  sure  that  the  dot  has  been  present 
ah  the  time,  but  it  will  not  have  been  attended  to.  It 
seems  that  one  can  attend  strictly  and  definitely  for  a 
very  short  time,  a  second  or  so.  In  addition  there  are 
waves  of  increased  effectiveness  which  come  and  go  every 
six  to  ten  seconds.  These  probably  depend  upon  fluc- 
tuating physiological  processes,  central  or  peripheral. 
If  one  mean  by  attending  to  the  same  thing,  attending 
to  a  general  subject  that  contains  changing  elements,  it 
is  possible  to  attend  for  several  hours  —  how  long  depends 


250  FUNDAMENTALS   OF  PSYCHOLOGY 

upon  the  nature  of  the  material,  the  strength  of  the  ob- 
server, and  other  conditions  that  vary  so  much  that  they 
cannot  be  measured. 

The  Conditions  of  Attention.  —  The  underlying  causes 
or  conditions  of  attention  are  to  be  found  in  the  antece- 
dents of  the  attending  process  in  the  individual  himself 
and  in  the  material  that  offers  itself  from  the  outside 
world.  On  the  one  hand,  the  individual  attends  because 
he  is  at  the  moment  or  in  general  of  such  a  character  that 
he  must  attend  to  the  particular  thing  at  the  particular 
time ;  on  the  other  hand,  the  characteristics  of  some 
stimulus  and  the  general  nature  of  the  environment  are 
such  that  he  cannot  avoid  noticing  it.  If  one  asks 
why  any  individual  notices  any  particular  thing  at  any 
particular  time,  one  will  find  the  answer  either  in  the 
nature  of  the  environment  or  of  the  individual.  The 
objective  conditions  may  be  found  in  the  attributes  of 
the  stimuli  that  are  attended  to  or,  negatively,  in 
the  character  of  the  other  stimuli  or  the  lack  of  all 
other  stimuli.  The  attributes  of  the  stimulus  that  are 
likely  to  arouse  attention  are  its  intensity,  its  size,  its 
contrast  with  the  surroundings.  Loud  sounds,  bright 
lights,  strong  odors  force  themselves  upon  consciousness, 
while  less  intense  stimuli  fail  to  attract  notice.  Also 
contrast  plays  a  part,  as  may  be  seen  from  the  fact  that 
a  fairly  bright  light  in  the  dark  attracts  as  much  attention 
as  a  brilliant  light  in  full  daylight,  or  a  light  footstep  in 
the  silence  of  the  night  as  much  as  the  automobile  horn 
in  the  midst  of  a  dense  street  traffic. 

Another  interesting  fact  in  connection  with  objective 
factors  is  that  change  is  an  essential  element  in  arousing 


ATTENTION   AND   SELECTION  25 1 

attention.  One  quickly  becomes  adapted  to  a  continu- 
ous stimulus  and  ceases  to  notice  it.  A  constant  light 
passes  unnoticed,  but  the  shadow  cast  by  the  passing 
of  a  cloud  at  once  intrudes  upon  consciousness.  The 
slight  noise  of  the  burning  gas  drops  into  the  background, 
and  as  Fechner  pointed  out,  the  miller  is  oblivious  to  the 
sound  of  his  mill,  but  the  slightest  change  induced  by  a 
defect  will  at  once  be  observed.  The  cessation  of  the 
stimulus  in  this  case  is  as  effective  as  an  increase  in  the 
sound.  A  clock  that  has  been  ticking  unnoticed  in  the 
study  will  be  noticed  when  it  stops  and  the  last  few  ticks 
will  be  heard,  —  sounds  that  would  have  had  no  effect 
upon  consciousness  had  they  not  ceased.  The  decrease 
in  the  size  of  an  object  moving  directly  aw^ay  from  us 
attracts  attention  almost  as  certainly  as  does  the  in- 
crease in  size  due  to  its  approach.  Each  of  these  effects 
of  objective  stimuli  might  be  explained  as  due  to  the 
universal  characteristics  of  man  or  to  the  inherited 
capacities  of  his  nervous  system.  But  since  they  are 
universal  to  all  nervous  systems  it  seems  more  simple 
to  regard  them  of  objective  origin,  than  to  assert  that 
man's  physical  organism  is  adjusted  through  heredity  to 
respond  to  stimuli  possessing  much  energy  and  particu- 
larly to  changes  in  the  amount  of  energy  affecting  a 
sense  organ. 

Subjective  Conditions.  —  More  truly  characteristic 
of  the  attention  processes  are  the  subjective  conditions. 
We  ordinarily  think  of  attention  as  a  free  act  by  which 
we  turn  to  one  thing  that  it  pleases  us  at  the  moment" 
to  notice  and  exclude  all  others.  But  frequently  there  is 
no  conscious  antecedent  desire  and,  where  there  is,  the 


252  FUNDAMENTALS   OF  PSYCHOLOGY 

desires  have  their  antecedents  in  the  experience  of  the 
individual  and  these  are  to  be  regarded  as  the  real  con- 
ditions of  his  attending.  Sometimes  he  knows  that  he 
desires  to  attend  because  of  the  antecedent  experiences, 
more  often  he  first  finds  himself  attending  and  never 
knows  why.  If  we  examine  the  nature  of  attention  in 
the  light  of  the  history  of  the  individual,  we  may  dis- 
tinguish five  different  groups  of  subjective  conditions. 
The  first  of  these  is  the  immediately  preceding  sensation. 
This  can  be  best  illustrated  by  hearing  out  overtones. 
If  one  is  listening  for  an  overtone  in  a  note  played  on  the 
piano,  and  has  heard  another  note  of  the  same  pitch  just 
before,  he  will  distinguish  it  easily,  while  unless  he  has 
considerable  training,  without  the  aid  of  the  note  the 
overtone  will  certainly  escape  him.  So  if  one  desires 
to  hear  the  first  overtone  of  c  on  the  piano,  and  will  strike 
c'  just  before  he  strikes  the  c,  he  will  notice  the  overtone, 
the  c' ,  without  difficulty.  Again  an  object  just  seen  in  a 
particular  place  will  strike  the  eye  when  one  seeks  for  it 
where  previously  it  would  not  have  been  noticed.  Very 
much  the  same  statements  may  be  made  of  the  idea  in 
mind.  If  one  can  call  up  a  definite  image  of  what  is  to  be 
seen,  the  corresponding  object  will  be  noticed.  It  is 
probable  that  the  skill  of  the  practiced  observer  in  hear- 
ing overtones  is  due  to  the  fact  that  he  can  recall  accu- 
rately the  tone  that  he  is  to  hear.  This  definite  image 
replaces  the  sensation  in  its  effect  of  making  the  overtone 
come  into  mind.  Similarly,  in  a  puzzle  picture,  to  recall 
the  concealed  face  in  its  actual  place  is  a  guarantee  that 
the  image  will  be  recognized  when  one  looks  a  second 
time.     The  image  definitely  recalled  serves  to  aid  the 


ATTENTION  AND   SELECTION  253 

entrance  of  the  corresponding  percept,  in  the  same  way 
as  does  the  immediately  preceding  sensation. 

Purpose  or  Mental  Attitude.  —  Most  important  and 
striking  of  these  subjective  conditions  is  the  influence 
of  a  factor  that  is  variously  designated  the  intention,  the 
purpose,  or  the  question  in  mind  at  the  moment.  When 
one  has  the  intention  of  seeing  a  particular  thing,  that 
thing  will  come  to  consciousness.  If  one  suggests  that 
you  look  for  a  cell  in  the  field  of  a  microscope,  the  prob- 
ability that  you  will  see  it  is  thereby  increased.  In  daily 
life  this  purpose  is  the  determining  factor  in  all  observa- 
tion. One  sees  or  hears  only  what  one  desires  to  hear,  or 
what  harmonizes  with  the  intention.  All  that  does  not 
harmonize  with  that  purpose,  unless  especially  favored 
by  objective  conditions  or  other  more  general  subjective 
conditions,  might  as  well  not  have  been  offered  to  the 
senses.  If  one  is  interested  in  what  an  individual  is 
saying,  one  will  not  notice  his  accent  no  matter  how  un- 
usual, and  if  one  is  a  phonetician  and  intent  on  the  study 
of  the  peculiarities  of  speech,  the  meaning  may  be  alto- 
gether lost.  One  does  not  notice  the  wall  paper  in  a  room 
unless  the  pattern  is  striking  or  one  is  deciding  on  wall 
paper  for  one's  self  and  so  has  that  as  a  dominant  purpose 
at  the  time.  Some  objects  that  have  been  under  one's 
eyes  for  years  may  never  have  been  noticed  unless  some 
purpose  made  it  desirable.  To  use  a  familiar  instance, 
the  reader  cannot  say  without  looking  whether  the  four 
on  his  watch  is  iv,  4,  or  iiii,  in  spite  of  the  number  of  times 
it  has  been  looked  at.  One  looks  to  learn  the  time,  not 
to  see  how  the  numerals  are  printed,  and  sees  just  what 
one  looks  for  and  nothing  else.     This  is  typical  of  most 


254  FUNDAMENTALS   OF  PSYCHOLOGY 

observation.  Man  is  blind  to  what  does  not  correspond 
to  his  momentary  purpose. 

This  purpose  or  mental  attitude  may  be  aroused,  either 
from  without  or  from  within.  From  without  it  may  be 
due  to  a  question  asked  by  another,  or  by  some  task  that 
has  been  set,  or  problem  that  has  been  raised  by  one  in 
authority.  From  within,  the  purpose  usually  arises  by 
a  suggestion  from  something  that  has  been  seen.  Some- 
thing external  or  internal  starts  a  train  of  associations. 
That  raises  a  question  about  an  object  present,  and  one 
looks  to  the  object  for  an  answer.  The  answer  to  the 
first  question  suggests  another  problem,  and  thus  a  train 
of  associations  in  the  series  of  questions  leads  to  one 
observation  after  another.  Observation  is  most  fre- 
quently the  result  of  a  series  of  problems  self-set  for  solu- 
tion. When  one  gets  the  problem  or  the  question,  finding 
the  answer  is  relatively  easy.  Without  the  problem,  ob- 
servation is  indiscriminate  and  relatively  unprofitable. 
In  this  sense  thought  usually  precedes  observation,  but 
the  thought  itself  grows  out  of  preceding  observation,  and 
so  both  are  to  be  regarded  as  parts  of  a  continuous  pro- 
gression in  which  each  thought  suggests  attention,  and 
the  results  of  each  attention,  a  new  thought  in  a  succes- 
sion broken  finally  by  the  irruption  of  an  intense  stimu- 
lus or  the  necessities  of  the  daily  life,  and  this  in  turn 
starts  a  new  series  of  questions. 

Education  and  Attention.  —  A  number  of  more  remote 
conditions  also  aid  in  preparing  an  individual  to  attend 
in  a  given  way  at  any  moment.  First  of  these  is  the 
earlier  training  and  previous  experience.  This  works 
in  two  ways:   in  the  first  place,  it  increases  capacity 


ATTENTION   AND    SELECTION  255 

for  observation  of  the  object  one  desires  to  know  about, 
and  it  largely  determines  what  one  desires  to  see.  The 
skill  of  experts  in  any  sort  of  observation  depends  upon 
training.  Expert  microscopists  in  any  realm,  musical 
critics,  the  skill  of  tea  and  mne  tasters,  and  of  the  woods- 
man in  tracking  game  and  in  seeing  the  signs  of  the  forest, 
all  come  from  training.  The  expertness  depends  in  part 
upon  knowing  what  to  look  for,  of  ha\^ng  in  mind  the 
problems  that  are  to  be  solved  in  a  particular  connection  ; 
in  part,  the  skill  in  discrimination  grows  mth  practice, 
and  is  probably  dependent  upon  a  number  of  physiologi- 
cal factors.  Training  has  also  ob\ious  effects  in  deter- 
mining what  sort  of  stimuli  shall  be  selected  for  atten- 
tion. This  works  in  two  ways.  In  the  first  place,  it 
helps  to  raise  questions,  to  organize  purposes.  One  can- 
not have  a  purpose  without  some  preliminary  knowledge 
of  the  thing  to  be  seen.  WTiat  to  look  for  in  animal 
structures  is  known  in  any  considerable  degree  only  by 
indi\'iduals  with  some  training  in  zoology.  The  trained 
machinist  has  at  once  a  series  of  questions  in  mind  as  he 
begins  to  examine  the  engine  that  you  have  called  him 
to  repair,  and  wdth  these  problems  that  have  grown  out 
of  his  experience  he  looks  with  a  definite  series  of  pur- 
poses and  easily  discovers  the  source  of  trouble.  But, 
secondly,  even  with  no  definitely  conscious  purpose,  one 
sees  the  things  that  one  has  been  accustomed  to  deal 
with,  or  that  one  has  been  trained  to  see.  The  printer 
unintentionally  sees  details  of  a  book  that  escape  the 
ordinary  reader. 

Social  Forces  in  Attention.  —  Still  another  group  of 
influences  that  play  an  important  part  are  the  outgrowth 


256  FUNDAMENTALS   OF  PSYCHOLOGY 

of  social  training.  These  are  found  in  the  ideals  that  one 
takes  from  society,  the  feeling  that  one  must  strive  to  see 
certain  things  because  of  the  fact  that  others  expect  it  to 
be  done.  One  attends  to  a  lesson  when  fatigued  or  when 
the  lesson  is  not  interesting  in  itself  because  one  desires 
to  make  a  good  record,  to  pass  an  examination.  One 
desires  to  make  a  good  record  again  for  the  sake  of  the 
approval  it  will  win  from  persons  one  respects.  Or  in  a 
more  permanent  effect,  one  desires  to  obtain  a  satisfactory 
knowledge  of  the  subject  for  the  value  it  may  have  in 
later  years,  or  in  the  profession  that  has  been  adopted. 
Again,  however,  choice  of  a  profession  depends  largely 
upon  the  social  favor  that  the  profession  has  in  the  group 
with  which  one  is  acquainted.  Even  the  belief  that  the 
particular  subject  will  help  in  the  profession  is  often 
taken  from  society.  It  is  a  preference  for  the  remote  as 
opposed  to  the  immediate  good,  but  the  more  remote  is 
accepted  as  good  and  obtains  impelling  force  because  of 
the  influence  of  society.  Society  approves  each  separate 
step,  as  well  as  the  attainment  of  the  end,  its  pressure  is 
felt  throughout  the  whole  course  of  the  attainment,  and 
thus  at  once  guides  and  compels  towards  that  end.  For 
our  present  purpose  it  may  be  regarded  as  the  source  of 
all  attention  from  constraint,  of  all  attention  against 
one's  momentary  desire. 

Heredity  and  Attention.  —  A  final  condition  of  atten- 
tion, most  remote  in  time,  is  found  in  the  hereditary  dis- 
position. This  heredity  may  be  either  immediate,  as  in 
the  inheritance  of  individual  traits,  or  remote,  as  in  atten- 
tion due  to  general  instinct.  The  former  is  less  easy  to 
illustrate  or  to  demonstrate,  but  it  seems  probable  from 


ATTENTION   AND    SELECTION  257 

special  studies  in  attention  and  more  general  studies 
in  heredity  that  certain  of  the  tastes  of  an  individual, 
which  are  either  derived  from  the  natural  direction  of 
his  attention  or  control  it  in  certain  respects,  are  inher- 
ited from  his  parents.  Galton  showed  that  marked  abil- 
ity and  interest  in  science  and  in  different  professions 
tend  to  run  in  families,  and  his  results  have  been  con- 
firmed by  numerous  studies.  The  more  general  heredity 
is  seen  in  the  fact  that  one  attends  to  moving  objects,  to 
personal  combats,  to  all  objects  that  are  Hkely  to  be 
especially  beneficial  or  injurious.  In  general,  if  one  asks 
why  one  attends  to  anything  at  a  particular  time,  the 
answer  may  be  found  in  the  nature  of  the  external  objects, 
or  in  the  different  mental  states  at  the  moment,  in  the 
experience  of  the  immediate  or  of  the  remote  past,  and 
finally  in  the  inheritance  of  the  individual.  As  has  been 
pointed  out,  these  cooperate  in  many  ways  and  vary 
independently  from  moment  to  moment,  but  could  we 
know  the  individual  completely  in  all  of  his  char- 
acteristics, his  past  history,  and  the  influences  working 
upon  him  from  the  en\'ironment,  it  would  be  possible  to 
say  fairly  closely,  even  with  our  present  knowledge,  what 
he  would  be  Hkely  to  attend  to. 

Control  of  Association.  —  Selection  is  quite  as  impor- 
tant in  controlHng  the  course  of  the  associations  or  in 
determining  the  ideas  that  shall  be  recalled  or  suggested, 
as  in  selecting  the  sensations  that  enter  consciousness. 
It  is  evident  that  the  mere  strength  of  connection  between 
ideas  would  give  only  a  rigid,  mechanically  determined 
series  of  thoughts  with  no  fiexibiUty  and  with  no  possi- 
bility of  logical  connections  nor  any  purposiveness  in 


258  FUNDAMENTALS   OF  PSYCHOLOGY 

the  thinking.  This  inadequacy  of  the  associative  con- 
nections to  explain  the  real  course  of  thinking  has  led 
many  to  abandon  the  theory  altogether,  in  spite  of  the 
fact  that  in  some  degree  the  importance  of  old  relations 
in  determining  what  shall  be  recalled  has  been  recognized 
all  through  the  history  of  psychology.  It  seems  more 
in  harmony  with  the  facts  to  accept  the  view  that  funda- 
mentally all  recall  goes  back  to  association,  that  each 
impression  recalled  must  be  suggested  by.  the  preceding, 
but  that  since  each  idea  has  been  connedUd  with  many 
others,  there  must  be  other  conditions  that  have  united 
to  bring  back  just  that  idea  and  no  other ;  or,  speaking  in 
advance  of  the  return  of  the  second,  that  which  shall  be 
aroused  of  the  many  ideas  that  have  been  connected  with 
the  first  depends  upon  a  number  of  other  forces,  and 
these  work  together  with  the  associative  tendency  in 
determining  the  recall. 

The  Goal  Idea.  —  Two  different  theories,  at  present 
current,  attempt  to  remedy  this  deficiency  in  the  doc- 
trine of  association.  One  suggested  by  Aschaffen- 
burg  and  much  used  by  the  psychiatrists  would  refer  the 
decision  of  the  course  of  ideas  to  the  effect  of  the  final 
idea  in  the  series,  what  they  call  the  goal  idea.  Thus 
if  the  goal  of  the  sentence  is  to  describe  the  weather, 
one  set  of  words  will  be  suggested,  if  to  decline  an  invi- 
tation, another  series  of  words  may  be  called  out,  even  if 
one  start  with  the  same  word.  When  the  course  of 
thought  leads  to  the  goal,  it  is  said  that  the  goal  idea 
dominated  it ;  if  it  wanders  at  random  by  virtue  of  the 
strength  of  the  connections  between  each  pair  of  ideas, 
we  have  to  do  with  another  sort  of  thought.     For  the 


ATTENTION  AND   SELECTION  259 

diagnosis  of  mental  disease,  thinking  dominated  by  goal 
ideas  is  normal,  while,  when  the  goal  idea  is  lacking  or 
is  of  slight  effect,  one  has  an  indication  of  mental  abnor- 
mality. There  can  be  no  doubt  that  these  terms  de- 
scribe an  important  difference  between  types  of  thought, 
that  associations  may  be  classified  along  these  lines. 
The  objection  is  that  it  gives  merely  a  descriptive  classi- 
fication rather  than  an  indication  of  the  effective  causes 
or  conditions.  One  cannot  think  of  the  last  idea  in  the 
series  as  exerting  an  influence  upon  those  that  precede  it. 
A  force  cannot  be  regarded  as  exerting  an  influence 
before  it  comes  into  being. 

Association  Controlled  by  Conditions  of  Attention.  — 
On  the  other  theory  the  same  facts  are  taken  into  con- 
sideration, but  the  explanation  is  in  terms  of  determinants 
rather  than  of  goals,  of  antecedent  rather  than  of  conse- 
quent events.  We  may  take  over  almost  bodily  our  con- 
ditions of  attention  and  apply  them  to  enumerate  the 
factors  that  determine  the  selection  of  one  possible  asso- 
ciate from  the  others.  What  correspond  to  the  objec- 
tive conditions  here  are  the  factors  that  determine  the 
strength  of  the  connection  between  one  element  and  those 
that  have  been  associated  with  it.  These  have  been 
shown  to  be  the  frequency  with  which  the  two  elements 
have  appeared  together,  the  recency  of  their  association, 
the  degree  in  which  they  were  attended  to  or  the  strength 
of  the  stimuli  that  called  out  a  response  at  the  time  of 
their  earlier  appearance,  and  the  primacy  of  the  associa- 
tion. Professor  Calkins  has  shown  that  the  first  time  an 
element  enters  into  an  association  with  another,  it  is  more 
likely  to  be  recalled  with  that  than  with  any  other  with 


26o  FUNDAMENTALS    OF   PSYCHOLOGY 

which  it  has  been  associated  at  a  later  period.  It  should 
be  added  that  Galton  found  that  very  many  of  the  ideas 
in  a  train  came  from  youth.  He  kept  a  list  of  ideas  that 
occurred  to  him  in  a  period,  and  then  traced  them  to  the 
time  of  their  original  experience.  Thirty-nine  per  cent 
were  found  to  come  from  boyhood  and  youth,  forty-six 
per  cent  from  the  period  of  subsequent  manhood,  and 
fifteen  per  cent  from  quite  recent  events.  This  indicates 
that  impressions  received  in  youth  are  better  retained 
and  are  stronger  in  their  connections  than  those  received 
at  later  times.  This  may  be  said  to  be  due,  either  to  pri- 
macy, to  the  greater  degree  of  retentiveness  of  the  asso- 
ciations first  formed,  or  to  the  greater  interest  in  the 
events  of  the  early  period  of  Kfe.  Professor  Calkins  also 
found  that  primacy  was  an  important  factor  in  the 
determination  of  the  strength  of  associates,  even  when 
they  were  formed  in  adult  Kfe.  A  number  of  experiments 
from  Ebbinghaus  prove  that  both  the  frequency  and 
recency  of  associations  are  important  elements  in  the 
determination  of  the  probability  of  recall.  Intensity 
does  not  lend  itself  so  well  to  experimentation,  but  chance 
observation  indicates  that  the  more  intense  stimulations 
leave  more  permanent  effects.  Under  this  head  come 
cases  in  which  the  intensity  is  of  subjective  origin,  is  due 
to  a  strong  feeling  or  to  close  attention.  It  has  been 
shown  that  the  degree  of  attention  increases  the  likeli- 
hood of  recall,  and,  while  the  experimental  case  for 
feeling  is  not  so  complete,  there  is  good  evidence  from 
everyday  life  that  this,  too,  serves  to  increase  the  close- 
ness of  the  connection.  As  a  result  of  these  objective 
conditions,  the  tendency  of  any  idea  or  partially  aroused 


ATTEXTIOX   AND    SELECTION  261 

neurone  to  arouse  some  other  is  constant.  Furthermore, 
were  this  strength  of  connection  the  only  thing  to  be  taken 
into  consideration,  it  would  be  very  difficult  for  the  con- 
nections to  be  changed.  The  idea  recalled  by  any  given 
idea  would  be  determined  once  and  for  all.  The  only 
way  one  association  could  be  broken  and  another 
substituted  would  be  to  permit  a  long  lapse  of  time  and 
the  formation  of  some  ver\'  strong  new  association.  It 
would  mean,  in  any  mind  subject  to  its  rule,  a  perfect 
mechanism  ^ith  no  possibility  of  breaking  away  from 
its  domination. 

Subjective  Conditions  of  Recall.  —  This  tyranny  of 
association  is  tempered  by  the  subjective  conditions  of 
attention  which  play  a  part  here,  as  well  as  in  the  en- 
trance of  sensations  to  consciousness.  By  far  the  most 
important  of  these  is  to  be  found  in  the  mental  attitude 
of  the  moment,  the  purpose  or  problem  that  is  set  the 
indi\'idual.  If  one  be  given  such  a  word  as  dog,  it  is 
possible  for  a  very  large  nmnber  of  associates  to  be  re- 
called. If,  however,  it  is  coupled  with  the  request  to 
name  the  class  to  which  it  belongs,  vertebrate,  animal, 
or  some  other  more  general  term  \\\\\  come.  While 
if  one  is  asked  to  give  an  instance  under  the  head,  a 
species  of  dog  or  the  name  of  some  particular  dog  is 
spoken.  There  is  still  room  for  selection  "^^ithin  the 
group,  but  the  group  itself  is  very  much  narrowed.  Sim- 
ilarly, if  two  numbers  are  sho^\TL  written  one  above  the 

other  and  a  line  dra\\Ti  beneath,  as    .  ,  6,  i8,  or  72  might 

be  associated  \\ith  them.  If  they  appear  in  a  check 
book  or  in  other  real  relations,   the  purpose  and  the 


262  FUNDAMENTALS   OF  PSYCHOLOGY 

knowledge  of  what  has  gone  before  serve  to  determine 
whether  one  or  another  shall  suggest  itself.  If  the  prob- 
lem is  set  by  another,  if  the  sum  appears  in  a  series  in 
which  one  has  been  asked  to  add,  subtract,  or  multiply, 
that  request  will  suffice  to  suggest  the  corresponding 
figure.  In  any  case,  either  the  task  that  has  been  set 
by  another,  the  demands  of  the  situation,  or  the  attitude 
that  one  may  happen  to  be  in  will  choose  from  among 
the  possible  associates  the  one  most  suitable.  In  addi- 
tion to  the  setting,  education  and  the  social  influences 
that  are  behind  voluntary  control  of  attention  also  have 
an  important  part  in  the  guidance  of  ideas.  While  as- 
sociation provides  the  possible  paths  along  which  ideas 
may  flow,  these  possibilities  are  made  actualities  by  the 
more  subjective  conditions  derived  from  the  earHer 
experience  and  present  intentions  of  the  individual,  and 
the  necessities  that  bear  upon  him  at  the  moment.  All 
the  factors  that  control  attention  serve  also  to  select 
the  associates. 

Forms  of  Attention.  —  It  is  customary  to  divide  at- 
tention, whether  applied  to  external  objects  or  to  the 
control  of  ideas,  into  three  groups,  —  voluntary,  involun- 
tary, and  non-voluntary.  In  popular  terms  the  basis  of 
division  is  with  reference  to  the  presence  or  absence  of 
the  will.  As  we  do  not  care  to  raise  the  question  of  the 
will  at  the  present  time,  we  can  make  the  classification 
with  reference  to  the  conditions  and  characteristics  of 
the  attention  process  discussed  above.  In  general,  it 
can  be  seen  that  the  attention  called  involuntary  corre- 
sponds to  attention  that  is  determined  altogether  by 
the  objective  factors.      We  attend  in  spite  of  ourselves 


ATTENTION   AND    SELECTION  263 

because  the  stimulus  is  strong  enough  to  force  itself  into 
consciousness,  whatever  the  state  of  consciousness  itself 
may  be  at  the  moment.  Attending  is  against  the  ^\i\\, 
against  the  desire  of  the  individual  at  the  moment.  We 
desire  to  read,  and  the  noises  of  the  street  force  them- 
selves upon  us,  or  we  desire  to  recall  the  book  in  which  a 
certain  statement  was  made,  and  a  large  number  of  ideas 
keep  forcing  themselves  upon  us.  In  the  latter  case  the 
associations  of  irrelevant  things  are  so  strong  that  the 
relevant  idea  is  kept  out. 

Voluntary  attention,  on  the  other  hand,  is  that  which  is 
determined  by  social  pressure.  The  desire  to  attend  is 
not  one  that  springs  spontaneously,  but  is  due  to  the 
impulsion  of  some  remote  end.  In  most  cases  a  struggle 
between  the  immediate  and  the  remote  good  or  pleasure 
is  involved.  Usually,  too,  as  has  been  said,  the  remote 
good  is  impressed  upon  us  by  some  form  of  social  pres- 
sure. The  approval  of  some  part  of  the  immediate  social 
group  is  necessary  to  make  the  distant  goal  more  attrac- 
tive than  the  inherently  pleasant  processes  that  would 
lead  us  away  from  it.  In  this  sense  social  pressure  is  the 
real  motive  force  behind  attention,  the  force  that  holds 
the  indi\ddual  to  the  less  pleasant  in  the  face  of  the  more 
pleasant*  The  characteristic  conscious  accompaniment 
of  voluntary  attention  is  a  mass  of  strain  sensations, 
sensations  which,  taken  together,  constitute  the  feeHng 
of  effort.  As  was  said  in  the  discussion  of  the  motor 
accompaniments  of  attention,  all  attention  involving 
conflict  of  motives  tends  to  arouse  diffuse  contractions 
in  a  number  of  muscles,  contractions  which  are  in  them- 
selves of  no  great  effect  upon  the  attention  process,  but 


264  FUNDAMENTALS   OF  PSYCHOLOGY 

which  are  accepted  as  an  indication  that  some  force  is 
active.  They  make  us  feel  active,  are  said  to  constitute 
a  sign  of  the  activity  of  the  will.  So  far  as  we  now  know, 
they  are  not  a  cause  but  an  effect,  they  are  a  sign,  not  of 
a  new  force,  but  of  a  conflict  of  conditions.  That  they 
have  no  good  effect  is  evident  from  the  fact  that  they  do 
jiot  accompany  the  most  effective  attention  and,  when 
they  appear,  usually  die  away  as  soon  as  the  highest 
stage  of  efficiency  of  attention  is  attained.  Voluntary 
attention  is  due  to  social  pressure  and  is  accompanied  by 
strain  sensations.  All  strain  sensations  taken  together 
constitute  what  we  call  effort. 

The  non- voluntary  form  of  attention  includes  all  classes 
not  previously  covered.  The  more  important  conditions 
are  the  mental  attitude  of  the  moment,  the  momentary 
purpose,  education,  and  heredity  or  instinct.  These 
seem  to  induce  attention  in  accordance  with  the  momen- 
tary nature  of  the  individual;  they  constitute  in  sum 
total  the  conditions  of  desire.  The  characteristic  accom- 
paniment of  this  form  of  attention  is  interest,  a  feeling  of 
pleasure  due  to  the  lack  of  conflict.  In  so  far  as  it  is 
strictly  interest,  it  is  a  pleasure  derived  from  the  mere 
act  of  attending,  rather  than  from  the  nature  of  the  thing 
attended  to.  Why  it  should  come  or  how  it  originates 
need  not  concern  us  here  ;  in  fact,  no  satisfactory  explana- 
tion has  been  given  for  it.  It  is  essential  to  emphasize 
that  both  it  and  the  feeling  of  effort  are  accompaniments 
or  effects,  not  causes,  —  are  signs  of  the  lack  of  conflict 
between  motives  on  the  one  hand,  and  of  conflict  on  the 
other.  After  all,  then,  these  three  divisions  of  attention 
are  not  entirely  distinct.     They  produce  the  same  effect 


ATTENTION  AND   SELECTION  265 

in  consciousness  ;  they  are  distinct  only  in  the  sensations 
of  effort  and  the  feehng  of  interest  which  accompany  them 
and  in  their  conditions,  and  these  shade  gradually  over 
into  each  other  without  sharp  hne  of  di\ision.  Atten- 
tion is  a  unitary  process. 

The  Physiological  Explanation  of  Attention.  —  On  its 
physiological  or  nervous  side,  attention  may  best  be  pic- 
tured as  a  preparation  of  one  tract  or  set  of  tracts  for 
action.  The  nature  of  this  preparation  in  advance  of  the 
entrance  of  an  idea  varies  for  the  different  subjective 
conditions.  The  immediately  preceding  stimulus  and 
the  idea  in  mind  can  be  pictured  as  due  to  the  effect  of 
a  pre\'ious  stimulation  of  the  same  tracts,  which  in 
consequence  are  still  partially  active  at  the  moment 
the  new  excitation  is  received.  This  corresponds  to  the 
fact  noted  in  the  preceding  chapter  that  the  nervous, 
response  continues  for  several  seconds  in  relatively  high 
degree  and  probably  for  a  considerably  longer  time  in- 
some  degree.  The  entering  stimulus,  finding  these  tracts 
already  active,  produces  a  greater  excitation  than  it  other-, 
wise  would  or,  if  several  stimuH  of  approximately  equal 
intensity  are  presenting  themselves,  that  one  produces 
its  effect  for  which  the  way  has  been  prepared  by  this 
partial  excitation.  The  influence  of  attitude  or  purpose 
is  the  result  of  the  spreading  to  a  large  number  of  asso- 
ciated paths  of  the  impulse  developed  by  the  stimulus 
that  arouses  the  attitude.  Many  of  the  neurones  con- 
nected mth  the  first  are  partially  aroused  by  it,  and  the 
entering  stimulus  needs  only  to  complete  the  excitation 
already  begun  to  become  conscious.  The  effect  of  edu- 
cation is  to  prepare  these  systems  of  paths  so  that  they 


266  FUNDAMENTALS    OF   PSYCHOLOGY 

may  be  excited  by  the  particular  stimuli  or  the  particular 
occasions.  It  is  essentially  a  process  of  organizing 
cerebral  cells  into  groups  so  that  one  entire  group,  as  well 
as  some  particular  associate,  may  be  aroused  or  partially 
aroused  by  a  suitable  stimulus.  In  addition  to  this 
process  of  partially  exciting  the  areas  that  are  to  respond, 
it  is  necessary  to  assume  that  other  groups  of  neurones 
are  active  in  facilitating  or  inhibiting  the  activity  of  the 
tracts  immediately  concerned.  An  activity  of  one  group 
makes  easier  the  arousing  of  certain  others  related  to  it, 
and  may  at  the  same  time  make  more  difficult  the  arousal 
of  other  groups.  An  idea  may  be  said  to  facilitate  cer- 
tain ideas  and  to  inhibit  others.  Each  of  these  processes 
may  be  regarded  as  an  explanation  of  the  selection,  either 
from  among  the  stimuli  which  seek  to  enter  conscious- 
ness, or  between  ideas  that  are  associated  with  the  partic- 
ular idea  that  serves  as  excitant.  Thus  on  the  nervous 
side,  the  course  of  impulses  is  determined  by  the  action 
of  very  large  numbers  of  neurones,  many  of  them  very 
remote  from  the  neurones  which  are  actually  the  seat 
of  the  processes  attended  to.  The  cortex  acts  as  a  unit 
rather  than  in  parts,  just  as,  on  the  side  of  consciousness, 
practically  all  experience  unites  in  determining  the  course 
of  any  single  element  of  consciousness. 

REFERENCES 

Pillsbury:  Attention. 

TiTCHENER :  Lectures  on  the  Psychology  of  Feeling  and  Attention. 


CIL\PTER   VIII 

PERCEPTION  —  SPACE 

So  far  we  have  been  deaHng  w-ith  the  preliminaries 
of  psychology,  with  the  physiological  substrate,  and  the 
fundamental  laws  and  the  elementary  structures  of 
mind.  We  must  now  turn  to  a  study  of  the  actual  mental 
content.  In  practice  we  think  not  at  all  of  sensations 
or  of  laws  of  association ;  on  the  contrary,  we  think 
always  of  things  and  of  events.  We  are  anxious  to  know, 
not  what  the  sensational  basis  mi  our  observations  may 
be,  but  the  nature  of  the  t)bject  seen,  what  it  is  in  itself 
independent  of  •ur  seeing.  We  deal  immediately  with 
objects  and  only  occasionally  are  we  interested  to 
know  what  the  mental  state  that  represents  the  object 
may  be.  We  must  now  begin  to  study  these  objects 
and  how  we  become  aware  of  them  or  derive  them  from 
the  immediate  sensations.  We  may  think  of  our  knowl- 
edge of  objects  as  dependent  upon  sensations.  Certain 
schools  of  psychologists  assert  that  they  are  complexes 
of  sensations,  that  things  are  compounded  of  sensation 
as  water  is  compounded  of  oxygen  and  hydrogen.  A 
little  observ'ation  shows  that  objects  are  not  merely 
sensations.  We  seldom  see  all  that  we  ascribe  to  the 
object  and,  on  the  contrary,  we  do  not  ascribe  to  the 
object  all  that  we  see.     From  our  present  point  of  view, 

267 


268  FUNDAMENTALS   OF   PSYCHOLOGY 

we  must  accept  the  common-sense  standpoint  that  the 
object  is  the  reahty,  and  that  the  sensation  is  an  ab- 
straction which  the  psychologist  has  developed  in  an  en- 
deavor to  understand  the  actual  experiences.  The  same 
statement  may  be  made  of  thoughts  and  even  memories. 
When  we  remember  we  do  not  reinstate  the  event  or 
even  the  perception  of  the  event,  we  only  refer  to  it. 
Even  more  truly  in  thought  we  have  assurance  that  things 
are  of  a  certain  form  but  we  do  not  reinstate  them. 
We  think  of  the  objects  and  their  relations  alone. 

It  is  evident,  then,  that  we  must  distinguish  between 
the  object  and  the  mental  content  that  we  have  been 
considering  heretofore.  The  psychologist  naturally  in- 
clines to  the  view  that  what  he  has  discovered  to  be 
the  immediate  content  —  the  sensations  and  the  cen- 
trally excited  sensations  —  are  the  realities  of  mind, 
while  the  common-sense  man  insists  that  he  has  objects 
in  mind  and  objects  alone.  While  this  question  borders 
upon  one  of  the  fields  most  hotly  contested  among 
philosophers  to-day,  and  while  we  need  attempt  to  give 
no  final  decision,  it  is  possible  to  state  a  position  which 
will  sufficiently  reconcile  conflicting  opinions  to  give  us 
a  satisfactory  basis  for  our  further  discussions.  First 
we  must  admit  that  the  naive  mind  and  all  minds  in 
naive  moments  deal  directly  with  objects.  Secondly 
these  objects  are  not  merely  compounds  of  mental  ele- 
ments. But,  on  the  other  hand,  we  can  obtain  a  knowl- 
edge of  these  objects  only  through  the  senses,  and  in 
many  cases  they  can  be  recalled  or  reinstated  only  by 
means  of  centrally  excited  sensations.  Two  attitudes 
may  be  taken  towards  the  fact.     One  would  assert  that 


PERCEPTI#N  —  SPACE  269 

by  some  process  of  completion  or  perfection  the  sensa- 
tions and  other  mental  elements  may  be  developed  into 
objects  or  more  perfect  counterparts  of  objects  than  are 
the  bare  sensations.  The  other,  the  object,  is  only 
meant  or  represented.  The  representative  is  not  the 
object  as  we  think  it,  it  need  not  be  Hke  that  object,  but 
yet  does  duty  for  it  in  all  mental  operations.  We  may 
grant  for  the  present  that  there  is  something  of  both  of 
these  processes.  What  we  see  is  corrected  and  de- 
veloped in  certain  respects  to  constitute  a  real  mental 
state  which  replaces  the  bare  sensations.  At  the  same 
time  all  that  is  intended  is  never  given  in  tke  mental 
states.  The  mental  content  merely  means  what  we  are 
thinking  about;  it  does  not  reproduce  it  or  constitute 
it. 

In  much  of  the  discussion  to  follow  we  shall  be  con- 
cerned mth  tracing  the  factors  that  aid  in  the  trans- 
formation of  the  sensations  into  objects.  We  ^all 
endeavor  to  discover  what  it  is  that  determines  the 
transformation,  and  also  keep  constantly  in  mind  the 
problem  of  the  way  in  which  elementary  mental  states 
come  to  mean  that  which  they  are  not.  We  can  expect 
to  form  a  decision  as  to  the  nature  of  the  meaning  and  the 
difference  between  the  mere  mental  state  and  the  thing 
it  represents  only  after  an  empirical  study  of  the  many 
different  facts. 

Temporally  first  and  in  many  ways  simplest  of  the 
concrete  mentaljprocesses  is  perception,  the  appreciation 
of  things  as' real  objects.  An  object  may  be  considered 
and  has  been  considered  as  a  group  of  sensations  entering 
consciousness  together.     If  one  were  to  accept  the  theory 


270  FUNDAMENTALS   OF   PSYCHOLOGY 

that  a  percept  is  a  compound  of  sensations,  the  perception 
of  a  bell  might  be  said  to  be  composed  of  a  group  of  visual 
sensations,  colors  of  certain  shapes,  tones  of  a  given 
quahty,  sensations  of  pressure  and  temperature,  all 
grouped  in  a  definite  position  at  a/definite  distance. 
Closely  examined,  however,  this  description  is  soon  seen 
to  be  inadequate.  In  the  first  place  psiixpis  involve 
more  than  sensations.  Frequently,  in  fact  usually, 
one  adds  to  the  actually  given  sensations  memory 
qualities  that  are  not  present  at  the  time.  As  one  hears 
the  bell,  its  picture  is  recalled ;  the  sound  alone  cannot 
be  said  t*  constitute  the  percept.  Again,  more  is  in- 
volved in  the  percept  than  can  be  given  by  the  sensations 
alone  even  if  we  include  both  immediate  and  reinstated. 
Aristotle  found  it  necessary  to  provide  a  '  common  sense  ' 
that  should  remove  the  discrepancies  between  the  dif- 
ferent senses,  which  he  found  to  be  constantly  in 
evidence.  We  shall  see  that  this  correction  of  the  ex- 
perience, the  harmonization  of  elements,  plays  an  im- 
portant part  in  all  perceptions. 

Tonal  Fusion.  —  The  only  perception  that  approxi- 
mates the  bare  combination  of  sensations  into  a  larger 
or  more  complicated  whole  is  the  tonal  fusion,  the  combi- 
nation of  simple  notes  into  chords  or  of  fundamental 
and  overtones  to  constitute  the  timbre  of  a  musical 
instrument.  As  was  seen  in  the  discussion  of  tones^ 
the  chords  have  a  quality  which  varies  with  the  ratios  of 
the  vibration  rates  of  the  notes  that  combine  to  produce 
them.  This  quality  evidently  depends  upon  the  simul- 
taneous stimulation  of  the  sense  organ  or  cortex  by  these 
tones,  but  why  their  composition  should  give  rise  to  the 


PERCEPTION  —  SPACE 


271 


effects  that  are  produced  is  not  at  all  agreed  upon. 
Helmholtz  suggested  that  it  might  be  due  to  beats 
between  the  fundamentals  or  between  overtones  or 
fundamentals  and  overtones,  but  Stumpf  found  several 
cases  in  which  the  relative  degree  of  fusion  did  not  follow 
the  order  of  complexity  of  beats.  Stumpf  then  goes 
to  the  other  extreme,  insisting  that  the  primary  fact  is 
fusion,  that  this  is  closely  related  to  harmony,  and  can- 
not be  explained  in  any  way  other  than  by  ultimate  con- 
nections in  the  nervous  system.  Certain  pairs  of  tones 
arouse  more  nearly  the  same  processes  in  consciousness, 
have  what  he  calls  a  '  specific  synergy,'  which  makes  it 
very  difhcult  to  distinguish  them.  It  seems  that  in 
general  this  relation  becomes  less  and  less  close  as 
numerator  and  denominator  of  the  fractions  designating 
the  interval  relation  become  larger,  as,  e.g.,  one  passes 
from  the  |  of  the  fifth  to  the  f  of  the  major  second,  or 
the  1^  of  the  major  seventh.  No  attempt  is  made  to 
explain  why  the  '  specific  synergy  '  should  exist  between 
one  pair  of  tones  and  not  between  others.  Other  au- 
thorities assume  an  almost  mystical  connection  between 
the  tones  in  question  and  a  hypothetical  common 
ground  tone  to  which  each  might  be  related  as  an  over- 
tone. Some  appreciation  of  this  relationship  is  sup- 
posed to  determine  the  harmony,  or  its  lack.  Obviously 
there  is  no  simple  answer  to  the  question  why  certain 
tones  fuse. 

Even  if  tonal  fusion  is  mere  fusion  so  far  as  consonance 
is  concerned,  there  are  always  involved  in  the  total  appre- 
ciation of  a  tone  group  many  elements  derived  from 
earlier  experience.     That  the  most  pleasing  combination 


272  FUNDAMENTALS   OF   PSYCHOLOGY 

varies  with  the  training  of  the  individual,  is  different  for 
the  occidental  and  oriental,  and  for  the  occidental  music 
at  different  stages  in  its  development,  is  fair  evidence 
that  we  are  not  deaHng  here  with  a  mere  combination 
of  elements.  In  connection  with  the  same  interval  on 
different  instruments,  one  may  distinguish  old  memories 
that  serve  to  change  its  character  as  well  as  its  reference. 
In  distinguishing  and  remembering  intervals,  the  name 
of  the  complex  plays  a  considerable  part.  Some  in- 
terpretation is  added  to  the  mere  complex  of  sensations. 
Even  in  this  apparently  simplest  case  of  combination  of 
simple  sensations  to  make  a  total  percept,  there  are 
additions  from  memory,  and  there  are  interpretations 
derived  perhaps  from  very  complex  experiences  which 
play  a  part  in  determining  what  the  particular  experience 
shall  be. 

When  we  pass  to  percepts  in  which  reference  to  things 
is  more  explicit,  as  it  is  in  practically  all  perception,  the 
complexity  of  the  processes  involved  in  the  construction 
is  even  more  marked.  In  the  study  of  perception  of 
objects  in  general,  we  find  it  advantageous  to  consider 
first  the  more  general  characteristics  of  all  experience 
and  leave  to  the  last  the  illustrations  of  general  laws 
derived  from  the  particular  perceptions.  All  experiences 
occur  in  time,  and  we  are  accustomed  to  abstract  the  tem- 
poral characteristic  from  the  different  experiences  and 
to  regard  it  as  if  it  were  independent.  While  this  ab- 
stract time  undergoes  many  variations  according  to  the 
particular  experiences  that  occur  in  it,  it  is  convenient  to 
consider  this  phase  of  experience  apart  from  the  others, 
and  to  regard  the  changes  due  to  the  nature  of  the  filling 


PERCEPTION  —  SPACE  273 

as  exceptions  to  the  general  rule.  Space  also  is  involved 
in  the  perception  of  all  objects  and  is  directly  appre- 
ciated by  four  of  the  senses.  Other  general  aspects  of 
experience  are  motion  and  rhythm.  Each  of  these  can 
be  treated  apart  from  its  particular  content  and  this 
simplifies  the  treatment  of  the  perception  of  particular 
objects.     We  may  begin  with  the  discussion  of  space. 

The  Perception  of  Space 

Space  is  appreciated  by  means  of  at  least  four  senses, 
—  touch,  vision,  hearing,  and  the  kinaesthetic  sense. 
Of  these,  vision  gives  the  most  accurate  and  complete 
appreciation,  touch  combined  with  the  kinaesthetic  im- 
pressions stands  next  in  definiteness,  and  the  auditory 
space  last.  In  actual  practice  all  objects  that  are  recog- 
nized as  objects  are  given  a  position  in  space,  whether 
they  are  actually  sensed  or  merely  recalled.  In  the  other 
senses,  the  spatial  aspects  are  ascribed  t«  one  of  the  more 
definitely  spatial  senses  —  tastes  to  the  tactual  impres- 
sions also  received  from  the  tongue,  e.g.,  —  or  are  some- 
what indefinitely  referred  to  space  in  general.  Odors  are 
usually  ascribed  to  objects,  but  the  localization  is  always 
uncertain  and  the  quahty  may  be  thought  of  as  inde- 
pendent of  the  organ,  as  general  or  all  pervasive.  Not 
only  are  the  subordinate  sensations  referred  to  sight,  but 
there  is  much  cross  reference  between  the  higher  senses. 
Different  senses  predominate  in  different  individuals,  but 
in  all  space  interpretations  more  than  one  sense  are  in- 
volved. 

Three  different  complexities  of  the  space  problem  pre- 
sent themselves,  although  for  sight  and  kinaesthetic  im- 


274  FUNDAMENTALS    OF   PSYCHOLOGY 

pressions  alone  are  all  to  be  considered.  These  are  the 
appreciation  of  position,  of  extent  in  two  dimensions, 
and  of  distance  or  depth,  the  third  dimension.  The  skin 
appreciates  position  and  extent  alone ;  the  ear,  distance 
and  direction  alone.  We  can  start  with  the  simplest  . 
problem  in  each  sense  and  transfer  what  may  be  gained  1 
from  that  to  the  more  compHcated  constructions. 

Perception  of  Tactual  Space.  —  Theoretically  simplest  > 
of  the  space  probleins  is  the  appreciation  of  the  position 
of  a  point  upon  the  skin.  Experiments  have  frequently 
been  made  to  determine  how  accurately  a  spot  upon  j 
the  skin  may  be  localized.  If  one  attempt  to  touch  a  h^ 
spot  on  the  skin,  one  will  note  an  error  that  averages 
a  centimetre  or  so  on  the  wrist  or  on  the  back  of  the 
hand,  is  smaller  on  the  fingers,  and  considerably  larger 
on  the  portions  of  the  body  ordinarily  covered.  This 
simple  experiment  indicates  two  facts :  one,  that  there 
must  be  something  that  guides  the  movement,  some 
immediate  awareness  of  where  the  point  touched  is ; 
and  secondly,  that  this  knowledge  is  not  absolute,  that 
it  is  subject  to  error  and  more  or  less  variable.  One  of 
the  first  theoretical  attempts  to  determine  what  it  is 
that  gives  a  knowledge  of  position  was  made  by  Lotze. 
Lotze  pictured  the  self  as  somewhere  in  the  brain  and 
as  receiving  impressions  over  the  nerves  from  the  sur- 
face of  the  body.  Such  a  self  might  be  pictured  as  Con- 
stantly questioning  what  part  of  the  skin  gives  rise  to 
the  sensations  it  received  and  seeking  for  signs  that 
indicate  their  origin.  Lotze  asserted  that  the  sensations 
received  from  different  parts  of  the  skin  had  different 
qualities.      These  different  qualities  were  not  described 


PERCEPTION  —  SPACE  2^^ 

very  definitely,  but  apparently  were  due  in  part  td 
the  character  of  the  skin  and  the  amount  of  tissue  that 
lay  between  it  and  the  bone.  The  quality  of  any  spot 
on  the  skin  he  called  its  '  local  sign.'  If  you  will  try  to 
discover  this  local  sign  in  the  sensations  from  your  own 
skin,  you  will  find  it  very  difficult.  Careful  examina- 
tion of  the  sensations  fails  to  disclose  any  such  quality 
in  addition  to  the  ordinary  skin  sensations,  —  one  knows 
immediately  where  the  touch  is  but  does  not  know 
how  he  knows,  —  an  ahnost  universal  condition  in  per- 
ception. 

Indirect  methods  of  analyzing  the  local  sign  or  means 
of  locaKzation  indicate  that  it  is  dependent  in  part  upon 
the  nerve  stimulated.  When  a  member  has  been 
amputated,  the  sensations  from  the  stump  are  still 
referred  to  the  missing  part,  and  when  a  portion  of  the 
skin  has  been  displaced  by  a  surgical  operation  without 
severing  the  nerves  that  supply  it,  sensations  from  the 
skin  will  for  a  time  be  given  the  old  position.  It  is  true, 
too,  that  the  accuracy  of  localization  is  greatest  where  the 
nerve  endings  are  most  numerous.  These  factors  might 
be  explained  on  Lotze's  assumption  that  each  nerve  had 
a  '  local  sign.'  They  also  have  been  interpreted  to  mean 
that  localization  is  due  to  the  movements  called  out 
reflexly.  If  each  point  on  the  skin  were  connected  with 
a  set  of  motor  neurones  that  would  cause  the  hand  to 
move  to  the  point  touched  or  that  would  call  out  a  slight 
movement  toward  the  point,  the  movement  might  be 
used  as  a  sign  of  the  position.  This  motor  theory  receives 
some  support  from  the  fact  that  animals,  whose  brains 
have  been  removed,  and  men  in  their  sleep,  will  touch  the 


276  FUNDAMENTALS   OF  PSYCHOLOGY 

point  stimulated  with  a  fair  degree  of  accuracy.  That 
it  alone  is  not  sufficient  is  probable  from  the  fact  that 
the  normal  animal  makes  the  movement  with  greater 
accuracy.  Still  a  third  theory  would  make  the  localiza- 
tion due  to  the  association  of  other  sensations  with 
cutaneous  excitation.  Often  a  picture  of  the  point 
touched  comes  immediately  upon  contact.  However, 
no  one  of  these  theories  may  be  regarded  as  sufficient  in 
itself.  Rather  must  we  assume  that  all  have  acted 
together  to  give  a  notion  of  each  different  position 
on  the  skin.  As  different  points  have  been  touched,  the 
kinaesthetic  have  been  associated  with  the  visual  sensa- 
tions, and  these  with  the  sensations  of  contact  and  with 
any  other  impressions  that  may  be  concerned.  After 
the  notion  has  been  developed  it  is  called  up  by  any 
contact. 

The  '  Limen  of  Two-ness.'  —  Much  the  same  problem 
meets  us  in  connection  with  the  appreciatron  of  a  mini- 
mal extent.  This  has  been  studied  by  determining  the 
least  distance  at  which  two  points  might  be  appreciated 
as  two.  Weber,  who  made  the  first  experiments,  found 
that  this  distance  varied  from  approximately  i  mm.  on 
the  finger  tips  and  tip  of  the  tongue  to  40-60  mm.  on 
the  middle  of  the  back.  In  general  it  was  larger  on  the 
portions  of  the  body  ordinarily  covered  and,  on  the  limbs, 
decreased  regularly  from  the  centre  of  rotation  down- 
ward. Volkmann  noted  that  it  varies  approximately 
with  the  amount  of  motion  of  the  member  and  of  the  parts 
of  the  member  in  question.  Goldscheider  repeated  the 
experiments  by  putting  the  points  of  a  compass  upon 
pressure  spots,  and  found  that  two  points  might  be  dis- 


PERCEPTION  —  SPACE  277 

tinguished  when  the  points  were  on  contiguous  spots. 
His  values  varied  from  0.3-0.6  mm.  on  tongue  and 
finger  tip  to  4-6  mm.  on  the  back.  Later  experiments 
by  von  Frey  indicated  that  these  values  were  too  small 
unless  the  stimuli  were  applied  successively.  In  these 
experiments,  as  in  comparisons  in  general,  successive 
stimuli  are  judged  more  accurately  than  simultaneous 
stimuli.  It  is  also  to  be  noted  that  practice  and  sugges- 
tion have  marked  effects.  Values  may  be  reduced  one- 
half  or  more  in  a  few  weeks'  practice.  It  is  seen,  too,  that 
practice  on  one  part  of  the  body  wdU  have  an  effect  upon 
the  symmetrical  areas  that  have  not  themselves  been 
exercised. 

The  explanation  of  these  values  may  be  reduced  in 
part  to  a  matter  of  comparing  "  local  signs.'  WTien  two 
signs  of  position  are  much  alike,  they  are  confused  and 
made  to  constitute  one  point.  By  sign  of  position  may 
be  meant,  either  actual  sensor}'  quality  if  that  exist,  or 
two  movements  or  the  suggested  motion  from  one  to 
the  other,  or  reference  to  \isual  distances.  Improvement 
with  practice  is  suggestive  of  this  process  of  analysis  as 
is  also  the  greater  acuity  on  the  more  mobile  and  in  con- 
sequence more  used  members.  Larger  extents  probably 
depend  more  upon  movement  from  one  point  to  the 
other,  either  of  the  member  itself  or  of  another  exploring 
organ.  A  curious  illusion  that  arises  in  the  comparison 
of  filled  with  empty  space  would  indicate  that  the  nature 
of  the  stimulation  plays  a  part.  If  one  is  asked  to  com- 
pare a  single  empty  space  with  a  space  containing  other 
stimulated  points,  the  empty  space  seems  greater  than 
the  interrupted  space.     The  explanation  is  difficult  in 


278  FUNDAMENTALS    OF   PSYCHOLOGY 

terms  either  of  movement  or  analysis.  The  importance 
of  reference  to  vision  should  also  be  emphasized.  Many 
individuals  translate  cutaneous  sensations  into  \dsion 
and  do  not  appreciate  the  distance  until  this  translation 
is  complete.  This  statement  may  be  verified  if  one  will 
have  another  trace  outlines  on  the  skin,  or  press  objects 
of  different  shapes  against  it.  The  blind  must  of  course 
have  an  immediate  appreciation  in  terms  of  pure  cutane- 
ous impressions  or  of  movements.  How  these  different 
factors  cooperate  is  not  as  yet  known,  but  it  is  un- 
doubtedly a  process  that  is  much  more  complicated  than 
the  simple  theories  we  have  indicated  would  make 
possible. 

Retinal  Local  Sign.  —  If  one  may  explain  something 
of  the  spatial  perception  on  the  skin  by  reference  to  the 
influence  of  vision,  it  is  also  necessary  to  understand  how 
position  and  extent  may  be  perceived  on  the  retina. 
The  same  problems  meet  us  here  and  many  of  the  same 
facts  are  present  to  provide  the  data  for  discussion. 
There  is  a  lower  limit  of  distance  that  must  separate 
two  points  if  they  are  to  be  perceived  as  two.  On  the 
fovea  if  two  dots  or  Hnes  are  nearer  together  than  .004- 
.006  mm.,  or  an  angular  distance  of  6o''-9o'^  they  fuse 
into  a  single  line  or  dot.  This  may  be  regarded  as  the 
*  limen  of  two-ness  '  for  sight.  The  eft'ects  of  the  inabil- 
ity to  distinguish  lines  and  points  closer  together  than 
this  mininmm  can  be  seen  in  the  ability  to  distinguish 
letters  in  reading.  The  normal  eye  can  read  letters 
when  the  width  of  the  separate  lines  and  the  distances 
that  separate  them  are  each  1' .  The  Snellen  types  in  the 
adjoining  figure  can  be  read  at  a  distance  such  that  the 


PERCEPTION  —  SPACE  279 

lines  are  separated  by  this  amount  or  by  .004  mm.  on 
the  retina.  Stratton  found  that  if  two  vertical  lines 
placed  one  above  the  other  were  brought  together  at 
their  extremities,  a  break  in  the  Hne  could  be  noted 
when  they  were  displaced  "]"  only.  In  this  case,  how- 
ever, the  difference  in  direction  of  the  lines  probably  also 
plays  a  part ;  it  is  not  merely 
appreciation  of  the  distance 
between  points.  As  the  dis- 
tance that  separates  the  cen-  '^"  ^"  ~~  ^^  ^^  ^^^^^' 
tres  of  cones  in  the  fovea  is  only  about  /\.o"-()o" ,  it 
would  seem  that  stimuli  no  farther  apart  than  the  centres 
of  neighboring  cones  can  be  discriminated.  As  one  pro- 
ceeds outward  from  the  fovea,  the  acuity  diminishes 
very  rapidly.  Five  degrees  from  the  centre  it  has  been 
reduced  to  one-fourth  and  at  forty  degrees  to  one  two- 
hundredth  of  the  maximum  value.  In  twilight  vision, 
where  the  cones  are  not  involved,  acuity  is  approximately 
the  same  in  all  portions  of  the  field  beyond  ten  degrees 
from  the  centre.  It  is  zero  in  the  fovea  itself  and  rises 
very  rapidly  until  the  stimuH  affect  the  retina  five  to 
ten  degrees  distant  from  it. 

The  theories  of  the  appreciation  of  position  and  extent 
upon  the  retina  involve  the  same  principles  as  those  ad- 
vanced for  the  skin.  The  awareness  of  position  seems  to 
depend  in  some  way  upon  the  nerve  element  stimulated, 
as  is  e\idenced  by  the  fact  that  when  a  retinal  element  is 
displaced  it  still  gives  the  old  sign  of  position.  Thus 
Wundt  at  one  time  suffered  from  choroiditis  under  one 
small  portion  of  the  retina.  This  caused  a  swelling  of 
the  retina  and  finally  resulted  in  a  small  scotoma  or 


28o  FUNDAMENTALS    OF   PSYCHOLOGY 

blind  spot.  While  the  elements  of  the  retina  were  dis- 
placed in  this  region,  the  straight  lines  seen  on  it  were 
distorted,  and  it  was  only  after  the  rods  and  cones  had 
been  used  in  their  new  positions  for  a  considerable  time 
that  the  spatial  relations  became  normal  again.  This 
sign  of  position  that  attaches  to  the  retinal  element 
has  been  ascribed  to  the  conjectural  '  local  sign  ' 
and  to  movement.  Differences  in  the  qualities  of 
sensations  received  on  different  areas  of  the  retina 
have  been  suggested  as  furnishing  the  means  of  distin- 
guishing position.  Even  the  difference  in  the  quality 
of  a  color  has  been  suggested  as  a  sign.  In  the 
movement  theory  it  is  assumed  that  the  tendency  of 
the  eye  to  turn  in  such  a  way  that  the  point  attended  to 
shall  fall  upon  the  fovea  constitutes  the  mark  of  position. 
The  more  general  and  inclusive  the  final  explanation,  the 
greater  the  likelihood  that  it  will  be  correct.  It  is  prob- 
able that  the  idea  of  position  here,  too,  is  a  notion  that 
has  been  gradually  developed  through  experience  of  all 
possible  sorts,  that  it  includes  reference  to  motion,  to 
areas  as  known  on  the  skin,  and  particularly  to  the 
movement  of  the  fingers  over  surfaces  as  eye  and  lin- 
ger explore  them  together,  and  a  large  number  of  more 
general  practical  tests.  After  the  complex  has  developed, 
some  peculiarity  in  the  retinal  element  stimulated  or  the 
activities  aroused  by  the  stimulation  suggest  this  idea 
or  concept.  Either  such  a  highly  complex  concept  of 
position  whose  origin  has  been  lost  in  the  course  of  its 
development,  and  which  is  now  appreciated  onl}^  for 
its  meaning,  must  be  assumed  to  constitute  our  idea  of 
position,  or  one  must  leave  the  problem  unanswered. 


PERCEPTION  —  SPACE  28 1 

The  perception  of  greater  visual  extents  depends  .very 
largely  upon  the  eye  movements.  It  has  been  investi- 
gated with  more  care  for  the  eye  than  for  the  skin. 
Studies  in  the  comparison  of  two  lines  show  that 
the  appreciation  of  distance  follows  Weber's  law,  — • 
one  can  appreciate  an  addition  in  length  of  from  ^o-  to 
-^  to  a  horizontal  line,  an  average  of  about  gV-  Appre- 
ciation of  difference  in  the  length  of  vertical  lines  is 
slightly  less  accurate,  an  average  of  about  ^V-  This 
sHghter  degree  of  accuracy  in  perception  of  vertical 
movements  has  been  connected  with  the  fact  that  the 
vertical  movements  require  two  pairs  of  muscles  and  so 
a  greater  amount  of  effort  than  horizontal  movements. 
They  are  thus  less  accurate  and  more  difficult  to  compare. 
As  one  estimates  the  length  of  a  line,  the  eyes  move  from 
one  end  to  the  other  and  the  comparison  is  probably 
very  largely  in  terms  of  these  movements.  The-  quali- 
tative characteristics  or  group  of '  local  signs  '  may  also 
play  a  part  but  here,  as  in  the  liminal  values,  they 
have  not  been  clearly  discriminated. 

The  Eye  Muscles.  —  The  importance  of  eye  move- 
ment in  the  perception  of  space  makes  it  desirable  to  give 
a  brief  statement  of  the  muscular  mechanism.  The 
eye  is  moved  by  six  muscles  arranged  in  pairs  and  named, 
from  functions  and  attachments,  the  internal  and  ex- 
ternal recti,  the  inferior  and  superior  recti,  and  the 
inferior  and  superior  oblique.  The  recti  muscles  all 
spring  from  near  the  apex  of  the  eye  socket  and  pass 
directly  forward  to  their  point  of  attachment  on  the 
surface  of  the  eyeball.  The  superior  oblique  also  origi- 
nates at  the  apex  but  runs  forward  to  a  ring  of  cartilage 


282 


FUNDAMENTALS    OF   PSYCHOLOGY 


on  the  upper  nasal  rim  of  the  socket  and  then  turns 
backward  to  be  attached  behind  the  centre  of  the  upper 
surface  of  the  eyeball.  The  inferior  oblique  springs 
from  the  lower  nasal  rim  of  the  socket  and  passes  back 
to  a  point  behind  the  middle  of  the  lower  surface.  From 
the  fact  that  the  oblique  muscles  exert  their  pull  toward 
the  front,  they  turn  the  eyes  in  the  direction  opposed 


Fig.  68.  —  Muscles  of  the  eye.  rs,  superior  rectus;  rif,  rectus  inferior;  re, 
external  rectus ;  rit,  rectus  internus ;  os,  superior  oblique ;  oi,  inferior  oblique ; 
/,  tendon  of  superior  oblique  which  runs  through  the  membranous  pulley,  ii, 
on  nasal  wall  of  the  socket. 

to  their  names.  The  direction  in  which  the  muscles 
turn  the  eyeball  may  be  best  indicated  by  the  diagram 
taken  from  Hering.  It  will  be  seen  that  the  internal  and 
external  recti  muscles  turn  the  eye  in  an  approximately 
straight  line ;  all  the  others  turn  it  along  a  curve  and  if 
the  eye  is  to  be  moved  directly  up  or  directly  down, 
two  muscles  must  cooperate  (Fig.  69). 

The  eyeball  turns  about  a  point  about  1.3  mm.  behind 
the  centre  of  the  eye.  The  centre  of  rotation  is  13.5 
mm.  back  of  the  cornea.     It  should  not  be  assumed  that 


PERCEPTION  —  SPACE  283 

this  point  is  absolutely  fixed,  —  owing  to  the  loose  way  in 
which  the  eyeball  is  held  in  its  socket,  it  is  slightly  dis- 
placed as  it  turns,  and  the  centre  of  rotation  moves  with 
it.  Also  as  the  eyeball  turns,  it  is  rotated  more  or  less 
about  its  optic  axis.  This  is  called  torsion.  The 
amount  of  torsion  increases  with  the  amount  of  the  move- 
ment, but  is  always  present  even  for  slight  movements. 
Both  eyes  always  move  together.  A  single  impulse  is 
sent  simultaneously  to  the  same  muscles  of  both  eyes. 
It  is  as  if  they  were  a  team  of  horses  turned  by  a  single 
pull  on  a  pair  of  reins.  These  movements  follow  the  direc- 
tion of  attention,  as  was  said  in  an  earlier  chapter.  The 
only  conscious  antecedent  is  that  some  object  in  the  field 
of  vision  shall  catch  the  attention,  and  the  eye  muscles 
immediately  contract  in  a  way  to  bring  both  eyes  to 
fixate  the  object.  As  points  of  reference  for  eye  move- 
ments, one  may  distinguish  certain  positions.  What  is 
known  as  the  primary  position  is  that  which  the  eyes 
have  when  fixed  on  a  distant  object  in  the  median  plane 
and  a  Httle  (15°)  below  the  horizontal.  From  this, 
movements  may  be  made  in  any  direction  wuth  the  optic 
axes  parallel,  or  the  eyes  may  be  converged  upon  points 
in  the  median  plane  or  to  one  side  of  it.  These  positions 
have  been  called  secondary  and  tertiary,  but  no  agree- 
ment as  to  which  are  to  be  called  secondary  and  which 
tertiary  has  been  attained. 

The  fact  that  we  always  use  two  eyes  instead  of  one 
offers  several  problems  of  interest  as  to  how  two  im- 
pressions can  combine  in  one,  what  part  each  contributes, 
and  the  advantages  of  binocular  as  compared  with  monoc- 
ular vision.     In  general,  it  may  be  said  that  for  most 


284 


FUNDAMENTALS    OF   PSYCHOLOGY 


purposes  the  two  eyes  act  almost  as  one  organ.  If  a 
plane  surface  be  presented  to  both  eyes,  we  see  a  single 
one  that  is  not  appreciably  different  from  the  same  sur- 
face as  seen  by  a  single  retina.  When  different  objects 
are  presented  to  the  surfaces  of  the  two  retinas,  the  result 


n-«/. 

\ 

w 

r.int. 

ji* 

*0 

ao 

so 

10 

10 

20 

30 

*V 

oO 

: 

10 

Fig.  69. 


r.,W. 


Hering's  diagram  of  eye-movements,  showing  course  the  eye  would 
follow  if  pulled  by  each  muscle  singly. 


may  be  that  (i)  the  two  may  fuse  to  produce  a  new 
quahty,  (2)  one  may  suppress  the  other  entirely,  or 
(3)  first  one  may  be  seen,  then  the  other.  Colors  which 
fuse  when  they  fall  upon  the  same  surface  in  a  single  eye 
are  likely  to  fuse  when  one  stimulates  one  retina,  the 
other  the  other.     For  certain  individuals  there  may  be 


PERCEPTION  —  SPACE  285 

an  alternation.  Thus,  if  one  half  of  a  stereoscopic  slide 
be  red  and  the  other  blue,  when  looked  at  in  the  stereo- 
scope they  will  ordinarily  give  a  purple,  but  at  times 
and  in  part  of  the  field  an  individual  will  see  first  the  red 
and  then  the  blue.  Where  a  contour  of  any  kind  is 
presented  to  one  eye  and  a  plane  surface  to  the  other,  as 
in  Figure  70,  the  contours  will  be 
noticed  and  the  plane  surface  neg- 
lected. The  law  may  be  formu- 
lated in  the  statement  that  you 
see   what  means   most    to    you,       Fig  70. -stereoscope  slide 

-^    ,  that  shows  the  efifect  of  con- 

What  is  most  interesting,  while  tours.  (From  Titchener, 
you  neglect  the  unimportant  plane      "Experimental Psychology.") 

surface.  Where  two  colors  or  grays,  alike  except  in 
brightness,  are  combined,  the  result  is  a  single  color 
with  a  brightness  intermediate  between  that  of  the  two 
objects.  The  brightness  is  usually  a  little  greater  than 
the  average  for  the  two  stimuli.  Thus,  when  the  two  are 
of  the  same  brightness,  the  brightness  of  the  combined 
image  may  be  -^  greater  than  that  of  either  alone,  and 
when  they  are  very  different,  the  brighter  may  have  its 
brightness  reduced  by  the  darker.  This  latter  is  known 
as  Fechner's  paradox,  since  the  addition  of  the  fainter 
brightness  to  the  greater  reduces  rather  than  increases 
the  brighter.  A  contrast  color  may  also  be  induced 
in  one  eye  by  stimulation  of  the  other. 

Corresponding  Points.  —  Very  important  for  the  space 
problems  is  an  understanding  of  the  arrangement  of  the 
points  or  lines  that  are  seen  singly.  If  vertical  lines,  one 
on  one  half,  the  other  on  the  other  of  the  stereoscope 
slide*be  seen  in  the  stereoscope,  it  -will  be  found  that  the 


286  FUNDAMENTALS    OF   PSYCHOLOGY 

lines  will  be  seen  as  one  if  they  are  so  placed  that  the 
images  fall  on  corresponding  points,  i.e.,  on  points  that 
are  the  same  distance  from  the  fovea  and  in  the  same 
direction.  If  both  are  vertical  and  pass  through  the 
fovea,  they  will  be  seen  as  one ;  if  one  pass  through  the 
fovea,  the  other  through  a  point  one  degree  to  either 
side  of  it,  both  will  be  seen.  Corresponding  points  may 
be  defined  as  those  equidistant  from  the  fovea  and 
in  the  same  direction  from  it.  If  the  two  retinas  could 
be  placed  one  over  the  other  in  such  a  way  that  the 
foveas  and  the  vertical  and  horizontal  axes  coincided, 
then  all  points  that  were  superimposed  would  be  corre- 
sponding points.  Stated  in  terms  of  rays  of  light,  those 
rays  fall  upon  corresponding  points  which  make  the  same 
angle  with  the  lines  of  sight  of  each  eye  and  in  the 
same  direction.  The  line  of  sight  is  the  line  from 
the  fixation  point  to  the  fovea.  The  most  important 
problem  for  the  perception  of  space  is  to  determine  how 
much  two  stimuli  must  depart  from  correspondence  be- 
fore they  can  be  seen  as  two  or,  in  terms  of  our  first 
problem,  how  far  the  two  lines  on  the  stereoscopic  slide 
may  depart  from  correspondence  before  they  will  seem 
to  be  two.  Pulfrich^  and  Bourdon  ^  found  that  two 
objects  need  have  no  greater  deviation  from  corre- 
spondence than  from  5''  to  12''  for  the  deviation  to  be 
noticed.  This  is  about  the  same  as,  or  even  less  than, 
the  'limen  of  two-ness'  for  a  single  eye.  It  should  be 
added  that  the  lines  are  not  necessarily  seen  as  two, 
but  the  divergence  may   be   translated   into  depth,  as 

^  Physikal.  Zeitschrift,  1899,  No.  9. 
2  Revue  Philosophiquc,  vol.  25,  p.  74. 


PERCEPTION  —  SPACE  287 

will  be  seen  in  a  later  discussion.  Considerably  greater 
deviations  from  correspondence  may  take  place  without 
being  noticed  if  the  lines  are  horizontal  than  if  vertical. 
Why  two  points  should  thus  give  rise  to  but  a  single 
image  is  not  easy  to  say.  The  first  theory,  suggested 
by  Johannes  IM tiller,  was  that  it  was  due  to  the  fact  that 
corresponding  points  were  connected  with  the  same  half 
of  the  brain.  It  is  a  fact  that  the  right  half  of  each 
retina  is  connected  wdth  the  right  hemisphere,  and  each 
left  half  with  the  left  hemisphere.  There  is,  as  the 
diagram  (p.  59)  shows,  only  a  partial  crossing  at  the 
chiasma,  —  half  of  the  fibres  cross  and  half  go  uncrossed 
to  the  same  side  of  the  brain.  Miiller  assumed  that  these 
fibres  in  some  way  combine  in  the  cortex,  perhaps  con- 
nect with  the  same  cells,  and  so  give  rise  to  a  single 
image.  This  would  be  the  nativistic  explanation ;  the 
combination  would  be  due  to  the  innate  nervous  con- 
nections. The  empiricist,  however,  can  cite  numerous 
cases  in  which  this  correspondence  is  changed  by  ex- 
perience. Individuals  whose  eyes  are  badly  crossed, 
who  squint,  develop  a  new  set  of  corresponding  points ; 
the  points  that  have  been  used  in  seeing  the  same  object 
come  to  give  single  images,  or  else  the  image  from  one 
eye  is  disregarded.  Similarly,  horizontal  lines  may  be 
a  considerably  greater  distance  apart  than  vertical  ones 
and  still  correspond.  Under  those  circumstances  it 
is  more  likely  that  there  is  one  line  than  two.  If 
the  lines  be  vertical  and  deviate  very  slightly  from  cor- 
respondence, they  will  be  seen  as  two.  We  shall  see 
that  this  deviation  from  correspondence  of  vertical  lines 
is  an  important  factor  in  the  appreciation  of  distance 


288  FUNDAMENTALS    OF   PSYCHOLOGY 

and  so  is  noticed,  while  the  necessity  for  distinguishing 
horizontal  lines  is  relatively  slight.  The  empiricist's 
explanation  would  be  that  we  see  the  two  images  as  one 
because  tests  by  touch  or  other  senses  have  shown  that 
there  is  only  one  object  present  in  spite  of  the  two  images  ; 
we  have  learned  that  two  images  mean  one  object,  and 
the  positions  that  are  most  frequently  stimulated  to- 
gether by  a  single  object  become  corresponding  points. 
The  Horopter.  —  The  problems  of  binocular  vision  and 
corresponding  points  are  of  interest  because  of  the  light 
that  they  throw  upon  the  positions  that  objects  in  space 
must  occupy  if  they  are  to  be  seen  singly.  When  the 
eyes  are  converged  in  a  given  position,  there  is  only  one 
distance  from  which  rays  of  light  can  fall  upon  corre- 
sponding points.  The  distance  varies  as  the  direction 
varies,  but  the  locus  of  points  in  space  which  will  send 
rays  to  corresponding  points  is  strictly  limited.  Points 
nearer  or  more  remote  will  fall  upon  non-corresponding 
points  and  so  give  double  images.  The  locus  of  all 
points  that  fall  upon  corresponding  points  is  called  the 
horopter.  The  form  of  the  horopter  has  been  developed 
mathematically  in  great  detail.  Since  the  assumptions 
upon  which  the  computations  are  based  do  not  corre- 
spond accurately  to  the  actual  facts  of  vision,  we  need 
pay  little  attention  to  the  intricacies  of  the  results.  Two 
forms  of  the  horopter  may  be  mentioned.  When  the 
eyes  are  converged  upon  a  point  in  the  plane  half  way 
between  them,  the  horopter  is  a  circle  passing  through 
the  fixation  point  and  the  nodal  points  of  both  eyes. 
To  this  is  added  a  vertical  line  through  the  fixation 
point.     When  the  eyes  are  parallel,  all  points  at  an  in- 


PERCEPTION 


SPACE 


289 


finite  distance,  the  distance  at  which  parallel  lines  meet, 
would  fall  in  the  horopter,  theoretically.  In  practice, 
the  horopter  is  composed  of  all  points  beyond  a  point 

F 


si/. 


a    F      b  a     P' 

Fig.  71.  —  Miiller's  Horopter  Circle,  a  and  a',  b  and  b'  are  corresponding 
points.  Lines  drawn  from  these  points  through  the  nodal  point  will  meet  in  a 
circle  that  passes  through  the  fixation  point  F  and  through  the  two  nodal  points,- 
n  and  n'. 

where  the  departure  from  the  parallel  is  less  than  5'', 
the  least  disparateness  that  can  be  appreciated,  or  some 
2500  metres, 
u 


290  FUNDAMENTALS   OF   PSYCHOLOGY 

The  Perception  of  Distance.  —  We  have  now  to  con- 
sider the  application  of  the  different  facts  of  vision  so 
far  collected  to  the  perception  of  the  distance  of  objects 
from  us,  what  may  be  called  depth  or  the  third  dimension. 
We  may  speak  first  of  the  elements  which  are  derived 
from  the  structure  of  the  eyes  and  which  in  consequence 
are  usually  spoken  of  as  the  primary  or  physiological 
factors.  With  the  single  eye  the  most  important  is  the 
accommodation  of  the  lens  for  different  distanced.  As 
was  said  in  an  earlier  chapter,  when  a  near  object  is 
attended  to,  the  ciliary  muscle  is  contracted  and  this 
permits  the  lens  to  thicken  and  give  a  clear  image 
of  the  object.  On  the  other  hand,  when  a  more  distant 
object  is  attended  to,  the  ciliary  muscle  is  relaxed  and 
the  lens  is  flattened  by  the  tension  on  the  suspensory 
ligament  and  so  adapted  to  receive  a  clear  image 
from  distant  objects.  The  degree  of  strain  varies  in- 
versely as  the  distance,  and  is  apparently  interpreted 
to  mean  the  distance  of  the  object.  One  thinks  of  objects 
that  are  seen  with  much  strain  as  near,  those  that  are 
seen  without  strain  as  remote  (no  strain  is  required  for 
objects  more  than  about  50  feet  away).  As  is  usual 
in  all  perception,  these  factors  are  not  observed  for  them- 
selves ;   the  distance  alone  comes  to  consciousness. 

Convergence  as  a  Factor  in  Distance  Perception.  — 
When  two  eyes  are  used  for  the  appreciation  of  distance, 
estimates  are  much  more  ^.ccurate.  If  one  will  look  with 
one  eye  at  a  landscape,  one  will  notice  that  it  appears 
much  flatter  than  usual.  'Or  if  one  will  attempt  to  put 
a  finger  through  a  ring  held  sidewise  by  another  it  will 
be  found  very  difficult  when  one  eye  is  closed  although 


PERCEPTIO^^ 


SPACE 


291 


perfectly  easy  when  both  eyes  are  open.  New  factors 
ob\dously  must  be  added  when  both  eyes  are  used.  Two 
of  these  are  important.  One  is  muscular,  the  movements 
required  to  converge  the  eyes  upon  a  single  object. 
Distant  objects  are  \dewed  with  the  eyes  nearly  parallel 
and  with  the  muscles  fairly  completely  relaxed.  As  an 
object  comes  nearer,  it  is  necessary  to  contract  the 
internal  recti  muscles  if  the  eyes  are  to  converge  to 
see  it  with  the  foveas.  This  gives  rise  to  another  strain 
that  also  decreases  with  the  distance.  This  strain  both 
is  a  more  accurate  index  of  distance  and  can  be  used  to 
detect  distance  over  a  longer  range  than  the  strain  of 
accommodation.  If  one  compare  the  distance  of  a 
thread  seen  at  different  distances  first  mth  one  eye  then 
with  both  under  conditions  that  restrict  the  means  of 
determining  distance  to  the  muscular  adjustment,  it  is 
found  that  the  distances  that  can  be  distinguished  are 
much  less  in  the  latter  case  than  in  the  former.  This  is 
shown  in  the  accompanying  table  taken  from  Wundt. 


TABLE   I 


Uniocular 

BlN-OCUL.\R 

CoMP.^Rison 

Distance 

Limen 

Limen 

Relative  Limen 

cm. 

mm. 

mm. 

250^ 

12 

180 

8 

3-5 

1/50 

130 

2.0 

1/64 

100 

8 

80 

5 

2.0 

1/39 

70 

i-S 

1/45 

60 

I.O 

1/50 

40 

4-5 

292  FUNDAMENTALS   OF   PSYCHOLOGY 

The  distance  is  the  absolute  distance  from  the  eye, 
the  limen  the  dilTerence  in  distance  that  can  be  just 
noticed,  the  relative  limen,  the  limen  for  binocular 
vision  divided  by  the  absolute  distance.  This  it  will 
be  noticed  is  approximately  the  same  as  the  difference 
limen  for  the  comparison  of  horizontal  lines  on  a  flat 
surface,  in  which  movements  have  also  been  regarded 
as  playing  an  important  part. 

Double  Images  in  the  Perception  of  Distance.  —  Still 
another  indication  of  the  distance  of  objects  is  found  in 
the  amount  of  disparity  of  points  or  objects  on  the  two 
retinas.  One  may  be  said  to  get  a  different  image  of  a 
distance  with  each  eye.  If  one  hold  a  ruler  end  on  in 
front  of  the  eyes  and  close  first  one  eye  and  then  the 
other,  it  will  be  noted  that  the  image  shifts  as  the  eyes 
are  changed.  If  one  converges  upon  the  far  end,  the  near 
end  will  be  seen  double  with  both  eyes  open,  while  if  one 
looks  at  the  nearer  end,  the  farther  will  be  double.  In 
either  case  the  image  of  the  ruler  will  slant  from  the 
double  to  the  single  end.  These  double  images  will  not 
be  noticed  at  first  but  will  be  used  as  immediate  signs  of 
the  distance  of  one  end  from  the  other.  Similarly,  if  two 
threads  are  present  simultaneously  in  the  field  of  vision 
at  ditlerent  distances,  the  one  fixated  will  be  seen  single, 
the  other  double,  and  will  be  separated  by  a  space  that 
increases  with  the  distance  between  the  threads.  This 
doubleness  is  of  value  only  in  determining  the  distance 
between  two  objects  or  points,  not  for  the  determination 
of  the  absolute  distance  of  a  single  object.  The  degree 
of  doubleness  changes  with  each  position  of  the  eyes  as 
well  as  with  the  distance  of  the  object.     Given  the  ab- 


PERCEPTION  —  SPACE 


293 


solute  distance  of  any  point  of  reference,  the  distance 
of  any  other  point  from  that  in  the  field  of  vision  may  be 

A 


f  a a- 

Fig.  72.  —To  illustrate  crossed  and  uncrossed  images.  F  is  the  fixation 
point  and  is  seen  singly.  A  more  distant  point  A  is  projected  ujxin  points  a 
and  a'  on  the  retinas,  which  are  non-corresponding.  As  excitations  of  the  retina 
are  projected  to  the  plane  of  the  fixation  point,  they  are  seen  at  A'  and  A" 
and  are  therefore  uncrossed,  the  image  seen  with  the  right  eye  is  seen  to  the 
right  of  the  fixation  point  and  to  the  right  of  the  image  seen  with  the  left  eye. 
Objects  nearer  tham  the  fixation  point,  as  B,  will  also  be  projected  to  the  fixation 
plane  at  B'  and  B"  and  so  are  crossed,  the  image  on  the  right  retina  is  seen  as  if 
it  were  to  the  left  of  the  fixation  point  and  mce  versa. 

determined.     Not  only  may  the  distance  between  two 
points  be  determined  in  this  way  but  also  which  is  nearer. 


294  FUNDAMENTALS    OF   PSYCHOLOGY 

If  one  fixate  the  more  remote,  the  double  images  are 
crossed  ;  that  is,  the  one  on  the  right  is  seen  with  the  left 
eye,  and  vice  versa.  If  one  fixate  the  nearer,  the  more  re- 
mote gives  uncrossed  double  images.  This  can  be  tested 
by  closing  one  eye.  It  will  be  noticed  that  when  the 
farther  object  is  looked  at  and  one  eye  is  closed,  the  image 
on  the  opposite  side  disappears ;  when  the  nearer  object 
is  fixated,  the  image  on  the  same  side  disappears.  This 
comes  because  the  double  images  are  always  referred  to 
the  plane  of  the  fixation  point  in  considering  their  rela- 
tive position  as  on  the  right  or  on  the  left.  This  can  be 
seen  by  study  of  the  diagram  (Fig.  72). 

These  double  images  constitute  one  of  the  important 
features  in  estimating  depth  in  our  ordinary  perceptions. 
As  one  looks  at  any  landscape  with  the  eyes  converged 
upon  some  object  in  the  middle  distance,  all  nearer  ob- 
jects are  seen  double  in  crossed  images  ;  all  more  remote 
objects  are  seen  double  in  uncrossed  images,  and  the 
degree  of  doubleness  increases  with  the  distance  from 
the  object  fixated.  These  double  images  are  not  or- 
dinarily seen  for  themselves,  but  are  at  once  translated 
into  distance,  just  as  are  the  strains  of  accommodation 
and  convergence.  However,  they  can  be  noticed  with 
a  little  practice.  So  close  has  become  the  association 
between  double  images  and  the  perception  of  distance 
that  when  letters  are  printed  to  appear  double,  they 
seem  nearer  or  farther  even  when  viewed  with  a  single 
eye.  The  importance  of  the  double  images  may  be 
shown  by  the  use  of  the  ordinary  stereoscope  which 
depends  for  its  effect  upon  the  fact  that  the  two  pictures 
represent  the  image  that  would  be  seen,  one  by  the  left, 


PERCEPTION 


SPACE 


295 


the  other  by  the  right  eye,  were  one  standing  at  the  point 
occupied  by  the  double  camera  when  the  picture  was 
taken.     The  prisms  in  the  stereoscope  turn  the  rays  of 


Fig.  73.  —  Diagram  of  prism  stereoscope.     (From  Titchener,  "  Experimental 
Psychology-.") 


light  sufficiently  to  have  them  enter  the  eyes  as  if  they 
came  from  a  single  object  rather  than  from  two.  The 
difference  in  the  two  pictures  gives  the  same  degree  of 
doubleness  that  would  be  given  by  the  single  object,  and 


296 


FUNDAMENTALS    OF   PSYCHOLOGY 


is  interpreted  as  distance  just  as  it  is  in  actual  space  per- 
ception. Increasing  the  distance  between  the  cameras 
that  take  the  pictures  increases  the  apparent  depth. 

Pseudoscope    and    Teleostereoscope.  —  Even    more 
striking  is  the  effect  of  the  pseudoscope.     If  the  relations 

of  the  double  images  are 
reversed,  as  may  be  done 
in  the  stereoscope  by  sub- 
stituting the  picture  be- 
longing to  the  right  eye 
for  that  belonging  to  the 
left,  the  nearer  objects 
appear  farther  away,  the 
more  distant  nearer  than 
the  point  of  fixation.  The 
same  effect  may  be  ob- 
tained with  real  objects 
by  using  the  pseudoscope 
devised  by  Wheatstone. 
This  consists  of  two  right- 
angle  prisms  mounted  in 
tubes  that  can  be  brought 
one  before  each  eye. 
The  images  are  reversed 
in  passing  through  the 
prisms,  and  this  makes 
the  images  that  come  from  the  nearer  object  enter  the 
eyes  as  if  they  came  from  the  more  remote ;  the  char- 
acter of  the  double  images  is  reversed,  those  from  ob- 
jects more  remote  than  the  fixation  point  are  crossed, 
those  from  objects  nearer  than  the  fixation  point  are 


Fig.  74. 
scope. 


-  Diagram  of  prism  pseudo- 
(From  Titchener,  op.  cit.) 


PERCEPTION  —  SPACE  297 

uncrossed.  In  consequence,  the  distance  interpreta- 
tions are  also  reversed.  The  inside  of  a  mask  when 
viewed  through  the  stereoscope  wdll  appear  to  be  the 
outside,  the  nearer  of  two  threads  wdll  seem  to  be  more 
remote,  etc.  It  is  to  be  noted  that  the  effect  is  much 
easier  to  obtain  if  the  inside  of  the  mask  be  painted 
to  represent  the  outside  and  is  so  lighted  as  to  avoid 
strong  shadows.     Another  indication  of  the  importance 


/ 


\ 


/ 


X--[ --^--- hr  ^^ 


H^=^  ■ 

I        ^ 

Fig.  75.  —  Teleostereoscope.     (From  Titchener,  op.  cit.) 

of  double  images  in  the  perception  of  distance  is  furnished 
by  the  teleostereoscope.  This  instrument  consists  in 
principle  of  two  pairs  of  mirrors,  P,  P,  one  before  each 
eye,  and  another,  M,  M,  at  a  little  distance  to  the  outside 
to  receive  the  rays  of  light  from  the  object.  The  effect 
is  to  increase  the  degree  of  doubleness  and  to  make  the 
perception  of  distance  as  accurate  as  it  would  be  if  the 
eyes  were  as  far  apart  as  the  more  widely  separated 
mirrors  that  first  receive  the  rays  of  light.  The  course  of 
the  rays  may  be  made  out  from  the  figure.  A  similar 
device  is  used  in  the  better  field  glasses  at  present. 
Surfaces  of  prisms  supply  the  mirrors  and  these  are 
separated  by  a  much  smaller  distance  to  make  the  in- 
strument more  portable,  but  they  serve  to  increase 
markedly  the  accuracy  of  the  estimation  of  distance. 


298  FUNDAMENTALS   OF  PSYCHOLOGY 

These  three  factors,  the  strain  of  accommodating  the 
eye  to  see  different  distances,  the  strain  of  converging 
the  eyes  upon  an  object,  and  the  double  images,  consti- 
tute the  signs  of  depth  that  may  be  said  to  depend  upon 
the  structure  of  the  organs,  and  are  sometimes  called  the 
primary  factors.  They  vary  in  accuracy,  —  accommo- 
dation is  least  accurate,  convergence  about  five  times 
as  accurate,  and  double  images  much  more  accurate 
than  either  of  the  others.  They  also  vary  in  the  distance 
at  which  they  are  effective.  Accommodation  varies  for 
objects  that  are  nearer  than  fifty  feet,  convergence  up 
to  about  300  feet.  Under  the  best  conditions  double 
images  give  an  idea  of  distance  up  to  about  2500  yards. 
Beyond  that,  the  more  distant  objects  show  no  ap- 
preciable double  images,  although  of  course  all  nearer 
objects  are  seen  as  double.  In  each  case  the  distance 
alone  is  really  seen ;  the  strains  or  double  images  that 
have  been  mentioned  are  not  noticed.  The  distance 
directly  inferred  is  not  any  single  mental  image  or 
sensation,  any  more  than  is  the  local  sign,  but  is  ap- 
preciated as  just  distance. 

The  Psychological  Factors.  —  While  these  primary 
factors  are  most  accurate,  many  other  signs  of  distance 
are  of  great  value.  The  others  consist  of  changes  in 
the  character  of  the  image  as  the  distance  changes. 
They  are  the  secondary  or  psychological  factors.  Per- 
haps the  most  important  of  these  is  perspective.  The 
size  of  an  object  is  inversely  proportional  to  the  distance. 
If  one  knows  the  size  of  any  object  in  the  field  of 
vision,  it  is  altogether  possible  to  infer  its  distance 
from  its  apparent  size,  the  size  of  the  image.     The  im- 


PERCEPTION  —  SPACE  299 

portance  of  this  means  of  obtaining  an  idea  of  distance 
may  be  gathered  from  the  use  of  perspective  in  art. 
The  distance  ascribed  to  an  object  in  a  photograph  or 
painting  depends  very  largely  upon  its  size,  relative  to 
other  objects  in  the  photograph.  Here  as  in  the  other 
factors  the  estimates  of  distance  are  not  made  con- 
sciously, one  does  not  first  notice  the  diminished  size 
and  then  infer  how  far  away  the  object  must  be  to  give 
that  distance,  but  sees  the  distance  at  once  and  corrects 
the  size  of  the  object  in  accordance  with  his  estimate  of 
distance.  The  object  seems  to  be  of  full  size  and  at  the 
correct  distance.  The  tendency  to  overlook  the  differ- 
ence in  size  is  evident  from  the  relatively  late  develop- 
ment of  perspective  in  art.  The  early  paintings  and 
bas-reliefs  make  distant  objects  of  the  same  size  as  the 
nearer  ones.  Obviously  the  early  artist  had  not  noticed 
the  phenomenon  of  perspective  but  inferred  distance 
without  knowing  how.  Even  now  an  artist  often  draws 
his  distant  objects  larger  than  they  should  be. 

A  second  factor  under  this  head  is  the  higher  position 
of  more  distant  objects  in  the  field  of  view.  Objects 
on  a  flat  ground  plane  appear  to  rise  gradually  as  they 
go  away  from  the  eyes  and,  with  proper  allowance  for 
the  actual  height  of  the  object  above  the  ground  plane, 
the  relative  height  may  be  used  as  a  measure  of  distance. 
This  factor  was  recognized  by  the  early  artists.  Their 
distant  figures  are  placed  higher  than  the  nearer,  an 
arrangement  that  made  it  possible  to  show  the  more 
remote,  as  well  as  to  imitate  the  apparent  effects  of  dis- 
tance. The  haziness  or  distinctness  of  objects  is  also  an 
important  factor.     This  can  be  seen  from  the  tendency 


300  FUNDAAIENTALS   OF  PSYCHOLOGY 

to  mistake  distant  objects  for  near  where  the  air  is  par- 
ticularly clear.  In  theatres  it  is  customary  to  draw  a 
net  in  front  of  the  more  remote  parts  of  the  scene.  Dis- 
tant objects  also  are  blue.  Both  of  these  effects  are  due 
to  the  absorption  of  light  waves  by  the  air  intervening 
between  the  object  and  the  observer.  The  condition 
is  sometimes  called  air  perspective.  An  element  almost 
too  obvious  to  mention,  but  nevertheless  highly  impor- 
tant in  practice,  is  superposition.  The  partly  hidden 
object  must  be  more  remote  than  the  one  fully  seen. 

Motion  an  Aid  to  Distance  Perception.  —  Motion, 
both  of  the  observer  and  of  the  object,  plays  a  part  in  the 
perception  of  apparent  depth.  When  the  head  is  moved 
to  one  side,  all  objects  in  the  field  of  vision  are  displaced 
in  different  degrees.  If  one  is  looking  at  any  object  in 
the  middle  distance,  all  nearer  objects  shift  in  the  direc- 
tion opposite  to  the  movement,  all  more  remote  ones 
in  the  same  direction.  The  amount  of  the  apparent 
displacement  increases  with  the  distance  between  the 
object  and  the  fixation  point.  When  one  is  in  rapid 
motion  as  in  a  railway  carriage  or  an  automobile  and 
is  looking  at  a  point  in  the  middle  distance,  there  is  a 
constant  procession  of  the  near  objects  backward  and 
the  more  remote  objects  forward,  at  a  rate  that  depends 
upon  their  distance  and  the  rate  of  motion.  This  gives 
a  notion  of  distance.  When  objects  are  themselves  in 
motion,  the  apparent  rate  of  motion  compared  with  the 
usual  rate  of  the  object  at  a  standard  distance  serves  as 
an  indication  of  its  distance.  When  seen  from  a  rapidly 
moving  vehicle  objects  seem  smaller  than  usual  because 
they  seem  to  be  moving  much  more  rapidly  than  usual. 


PERCEPTION  —  SPACE  3OI 

This  means  that  they  are  regarded  as  much  nearer  than 
they  really  are,  and  this  by  the  habits  of  perspective 
means  that  they  should  be  interpreted  as  small. 

Shadows  in  Space  Perception.  —  Another  factor  that 
aids  in  determining  the  form  of  objects  in  the  third 
dimension  is  the  interpretation  put  upon  shadows  and 
high  lights.  The  nearer  surfaces  are  usually  well  illu- 
minated while  the  more  remote  are  more  or  less  in  the 
shadow.  This  is  translated  at  once  into  depth  or  dis- 
tance and  the  shadows  themselves  are  Httle  noticed. 
Shadows  are  much  used  by  the  artist,  in  fact  are 
quite  as  important  as  perspective  in  enabling  him  to 
represent  depth  in  the  contour  of  an  object  on  the  fiat 
canvas.  In  the  real  object  much  depends  upon  the 
knowledge  of  the  direction  from  which  the  Kght  comes 
or  from  assumptions  that  are  made  concerning  the  direc- 
tion. If  one  will  look  at  a  cameo  under  a  microscope 
which  reverses  the  image,  it  seems  to  become  an  in- 
taglio. The  high  lights  fall  on  the  side  that  they  would 
have  were  the  depth  relations  reversed,  and  with  that 
they  are  seen  as  if  reversed.  In  depressions  made  in 
steel  by  a  smooth  ball  where  the  hghts  are  coming  from 
all  sides  and  the  reflections  are  numerous,  it  is  quite 
easy  to  see  the  depression  as  a  protuberance. 

Depth  for  vision,  then,  is  appreciated  by  virtue  of  a 
number  of  differences  in  the  sensations  that  come  from 
the  muscles  of  the  eye,  external  and  internal;  in  the 
difference  in  an  object  as  it  is  seen  by  the  right  eye  and 
by  the  left ;  and  by  a  number  of  pecuHarities  of  the  image 
of  an  object  that  change  with  the  distance.  These  sen- 
sations are  not  fi.rst  seen  for  themselves  and  then  asso- 


302  FUNDAMENTALS    OF   PSYCHOLOGY 

dated  with  the  idea  of  distance ;  there  is  no  conscious 
use  made  of  them  in  estimating  distance,  but  as  a 
result  of  their  presence  the  object  is  at  once  seen  at  the 
corresponding  distance.  In  this  respect  the  third  dimen- 
sion is,  Hke  the  other  two  dimensions  and  the  idea  of 
position,  apparently  received  immediately  and  can  be 
analyzed  into  its  elements  only  indirectly. 

Auditory  Perception  of  Space.  —  One  other  sort  of 
perception  of  distance  needs  to  be  mentioned,  the  per- 
ception of  the  position  and  distance  of  sounds.  Unlike 
tactual  and  visual  sensations,  there  is  in  sound  no  really 
two-dimensional  space,  no  perception  of  objects  in  con- 
tact with  the  sense  organ,  but  merely  perception  of  the 
distance  and  direction  of  objects  that  give  rise  to  sounds. 
These  localizations  are  relatively  uncertain  and  in- 
definite. One  is  constantly  deceived  as  to  the  distance 
and  direction  of  sounds.  The  breathing  of  a  dog 
on  the  hearth  may  be  mistaken  for  distant  thunder 
or  some  other  intense  but  distant  noise.  Front  and 
back  are  often  confused.  Right  and  left  much  less 
often,  but  still  under  the  influence  of  suggestion,  con- 
fusions of  this  sort  are  far  from  infrequent.  Experi- 
ments indicate  that  the  primary  factor  in  the  perception 
of  distance  is  the  intensity  of  the  sound  as  compared 
with  the  sound  given  at  some  known  or  standard  dis- 
tance. This  implies,  first,  a  recognition  of  the  source 
of  the  sound,  then  an  association  between  the  present 
intensity  of  the  sound  and  the  distance  that  would  give 
the  particular  intensity.  A  locomotive  whistle  has  been 
heard  at  a  large  number  of  distances,  more  or  less 
accurately  observed  or  measured.     When  it  is  recognized, 


PERCEPTION  —  SPACE  303 

its  intensity  at  once  suggests  the  distance.  Similarly 
\\ith  any  familiar  sound.  If  the  sound  be  altogether 
unfamiliar,  recognition  of  distance  would  be  difficult, 
although  if  it  be  recognized  as  belonging  to  some  known 
class,  an  estimate  can  usually  be  made. 

The  Appreciation  of  the  Direction  of  Sounds.  —  Per- 
ception of  direction  depends  upon  three  factors,  —  the 
relative  intensity  of  the  sound  heard  with  each  ear,  the 
timbre  of  the  sound,  and  its  intensity.  A  sound  on  the 
left  vdW  excite  the  left  ear  more  than  the  right.  Some 
more  accurate  notion  of  the  direction  of  the  sound  may 
be  gathered  from  the  relative  strength  of  the  effects 
upon  the  two  ears.  Distinguishing  between  before  and 
behind  offers  greater  difficulties.  With  pure  tones  it  is 
almost  impossible.  If  two  tuning  forks  of  the  same  pitch 
be  vibrating,  one  directly  in  front,  the  other  directly 
behind,  and  one  be  stopped,  it  is  almost  impossible  to 
tell  which  is  still  sounding.  The  percentage  of  mistakes 
will  approach  fifty.  If  the  sounds  be  complex,  are  noises, 
or  from  instruments  rich  in  overtones,  fewer  mistakes 
are  made.  This  suggests  that  the  quaHty  of  the  tone 
is  in  some  way  modified  by  the  direction  from  which 
the  tone  comes.  Angell  asserts  that  this  may  be  due  to 
the  way  in  which  the  various  overtones  are  modified 
when  the  tone  strikes  the  outer  ear.  From  one  direction, 
one  overtone  or  group  of  overtones  wdll  be  reenforced, 
from  another  direction  another  will  be  strengthened, 
and  the  resulting  complex  tones  are  interpreted  as  mean- 
ing direction.  Myers  ^  has  shown  experimentally  that 
changes  in  the  timbre  of  a  tone  will  induce  changes  in 

^C.  S.  Myers,  Proc.  Royal  Society.     B.  Vol.  88,  1914,  pp.  267-284. 


304  FUNDAMENTALS   OF   PSYCHOLOGY 

localization.  If  a  tone  be  sounded  directly  in  front 
until  the  observer  has  acquired  practice  in  localizing, 
and  then  the  component  parts  of  the  tone  be  changed  to 
give  it  a  different  quality,  the  sound,  although  still 
coming  from  in  front,  will  be  localized  in  some  other 
position.  Changes  in  the  intensity  of  the  sound  also 
induce  similar  mistakes.  The  importance  of  the  changed 
intensities  is  to  be  related  to  the  fact  that  sounds  from  in 
front  are  caught  by  the  pinna,  the  outer  ear,  and  f ocussed 
into  the  meatus,  while  sounds  from  behind  are  diminished 
in  volume.  When  the  absolute  intensity  and  the  dis- 
tance of  a  sound  are  known  or  may  be  conjectured, 
the  position  of  the  sound  as  in  front  -of  or  behind  the 
plane  of  the  ears  can  be  estimated  in  terms  of  intensity. 
Direction  of  sounds,  then,  is  estimated  in  terms  of  the 
relative  intensities  of  the  tones  as  heard  by  the  two  ears, 
and  by  the  timbre  and  intensity  of  the  tone.  It  has  at 
times  been  conjectured  that  direction  might  be  estimated 
in  terms  of  the  stimulation  of  the  skin  in  the  neighborhood 
of  the  ears,  or  on  other  portions  of  the  face.  This  as- 
sumption is  improbable  in  itself,  since  sound  waves  are 
not  sufficiently  intense  to  excite  the  organs  of  pressure. 
Myers  found,  too,  that  when  he  placed  short  rubber 
tubes  in  the  ears,  all  capacity  for  estimating  the  position 
of  sounds  disappeared.  These  tubes  made  it  impossible 
for  the  external  ear  to  modify  the  quaHty  of  the  tones  or 
their  intensity  but  left  the  tactual  sensations  unaffected. 
Were  the  skin  to  play  any  part  in  the  determination,  the 
tubes  should  have  had  no  influence. 

The  Auditory  Space  of  the  Blind.  —  Auditory  appre- 
ciation of  space  plays  a  much  larger  part  for  the  blind, 


PERCEPTION 


SPACE 


305 


who  must  trust  to  the  ears  for  a  knowledge  of  the  position 
of  all  distant  objects.  A  blind  man  appreciates  the 
distance  of  objects  fairly  accurately  through  the  effect 
they  have  upon  the  quahty  of  famihar  sounds,  such  as 
his  footsteps  or  the  tapping  of  his  cane.  Large  objects 
reflect  the  sound,  give  echoes,  or  modify  its  quality. 
It  is  easy  to  distinguish  the  difference  in  the  voice  when 


ABC 

D  E  F 


Fig.  76. 


Illusions  due  to  overestimation  of  the  vertical.     (From  Titchener, 
op.  cit.) 


speaking  in  a  room  filled  \^dth  people  and  when  speaking 
in  an  empty  room.  Even  the  presence  of  furniture  in  a 
room  in  an  ordinary  dwelling  has  a  pronounced  effect. 
The  bHnd  man  learns  to  distinguish  all  of  these  differ- 
ences and  to  learn  what  they  mean  as  to  the  presence 
and  arrangement  of  objects.  That  the  blind  depend 
upon  the  reflection  of  sounds  in  avoiding  objects  was 
shown  by  Dr.  Heller,^  director  of  a  blind  asylum,  who 
on  one  occasion  provided  his  pupils  with  felt  sHppers 
^  Heller,  Studien  zur  blinden  Psychologic. 


3o6 


FUNDAMENTALS   OF  PSYCHOLOGY 


in  place  of  their  heavy  shoes  and  watched  them  at  their 
play.  He  found  that  they  no  longer  avoided  obstacles 
and  would  come  into  conflict  with  many  of  them.  The 
sound  from  their  footsteps  could  no  longer  be  heard 


Fig.  77.  —Illusions  of  filled  and  empty  space.     (From  Titchcner,  op.  cit.) 

sufficiently  for  the  modifications  by  the  obstacles  to 
be  noticed.  It  seems,  then,  that  for  the  Wind  much  of 
the  perception  of  space  depends  upon  the  modification 
of  the  sounds  of  the  footsteps  and  of  other  familiar 
sounds  by  walls  and  objects  in  general. 


PERCEPTION  —  SPACE  307 

Optical  Illusions.  —  Very  interesting  as  illustrating  the 
factors  that  lead  to  the  perception  of  space  and  of  per- 
ception in  general  are  certain  illusions  of  \dsual  space  per- 
ception. Many  more  forms  of  optical  illusion  are  known 
than  we  can  describe,  and  more  explanations  have  been 
offered  than  we  have  room  to  mention,  but  we  may  select 
a  few  illusions  as  illustrations  of  the  more  important 
theories.  One  of  the  simplest  types  is  seen  in  mis- 
taken estimates  of  the  length  of  Hnes  or  distances  between 
dots.  Thus  horizontal  lines  seem  shorter  than  vertical 
lines  of  the  same  length  (Fig.  76,  A,  D),  interrupted 
spaces  seem  longer  than  uninterrupted  or  unfilled  spaces 
or  Hnes.  Figure  77,  A,  B,  indicates  that  filled  space, 
space  filled  ^vith  a  number  of  dots,  or  a  solid  line  seems 
longer  than  the  empty  space  of  the  same  length ;  Figure 
E,  that  a  square  with  numerous  vertical  Hnes  drawn 
across  it  seems  longer  than  it  is  high.  Even  these  simple 
illusions  have  given  rise  to  much  difference  of  opinion. 
One  theory  would  explain  all  in  terms  of  eye  movement. 
It  is  said  that  the  fact  that  the  up  and  down  move- 
ments of  the  eyes  involve  a  waste  of  effort,  owing  to  the 
tendency  of  each  superior  and  inferior  rectus  muscle  to 
pull  the  eye  in  as  weH  as  up,  a  tendency  which  must  be 
counteracted  by  the  obHque  muscles  and  so  gives  rise 
to  greater  amounts  of  strain,  leads  to  the  overestima- 
tion.  Experiments  made  \\ith  the  observer  lying  on  his 
side  which  show  that  the  vertical  distance  is  still  over- 
estimated would  tend  to  disprove  this  theory.  Helm- 
holtz  suggested  that  the  overestimation  of  the  vertical 
was  due  to  a  habit  derived  from  the  use  of  perspective. 
Vertical  lines  in  space,  as  in  a  picture,  usually  or  fre- 


308  FUNDAMENTALS   OF  PSYCHOLOGY 

quently  represent  greater  horizontal  distances  seen  in 
perspective,  and  so  we  form  the  habit  of  overestimating 
all  vertical  Unes. 

According  to  one  theory  the  interrupted  spaces  are 
made  to  seem  longer  by  a  similar  exaggeration  of  the 
apparent  movements  through  the  numerous  stops  that 
are  made  at  each  of  the  intervening  dots  or  lines.  That 
this  is  not  the  whole  story  can  be  seen  from  the  fact 
that  where  the  dots  are  relatively  few  (Fig.  77,-0),  one  or 
two  only  in  the  length  of  the  line,  the  distance  is  under- 
estimated rather  than  overestimated.  The  other  ex- 
planation is  that  the  filled  spaces  give  an  impression  of 
multiplicity  and  this  is  confused  with  the  length  of  the 
line.  The  apparent  shortening  of  the  line  when  only 
one  or  two  dots  are  inserted  is  apparently  due  to  a  con- 
fusion between  the  separate  spaces  and  the  total  length. 
The  full  line  tends  to  be  compared  with  the  smaller 
divisions  of  the  divided  line.  This  same  confusion  is 
better  illustrated  in  the  comparison  of  the  vertical  and 
the  horizontal  lines  in  Figure  76,  E.  Here  the  vertical  is 
compared  with  the  halves  of  the  base  line.  Where 
erected  at  the  end  of  the  line,  the  vertical  is  slightly 
overestimated  but  relatively  very  slightly  (Fig.  76,  D). 
This  effect  can  be  eliminated  by  turning  the  book  ninety 
degrees,  while  the  illusion  in  E  persists. 

The  Miiller-Lyer  Illusion.  —  One  of  the  most  striking 
and  most  discussed  of  all  is  the  Miiller-Lyer  illusion. 
It  will  be  noted  that  the  Hne,  bounded  by  oblique  lines 
that  turn  in,  seems  much  shorter  than  the  other  line 
of  the  same  length  bounded  by  oblique  lines  that  turn 
out.     The  explanations  offered  for  this  illusion  include 


PERCEPTION  —  SPACE  3^9 

practicaUy  aU  that  may  be  offered  for  any.  Wundt 
suggested  that  it  was  due  to  eye  movements,  that  the 
eyes  were  checked  too  soon  by  the  hues  that  turn  in, 
and  carried  on  by  the  Hues  that  turn  out.  It  is  suggested 
that  it  be  explained  on  the  basis  of  perspective,  that  one 


Fig.  78.  —  Various  forms  of  the  MiiUer-Lyer  lUusion. 


represents  an  open  book  or  similar  figure  with  the  back 
towards  the  observer,  the  other  an  open  book,  much 
larger,  with  covers  opened  towards  the  observer.  In  the 
first  case  the  actual  length  of  the  book  is  the  length  of 
the  Hne  itself ;  in  the  other,  the  length  would  be  from 
the  end  of  the  obHque  Hnes  at  their  greatest  separation. 
StiU  another  theory  is  that  one  confuses  the  whole  spaces 


310  FUNDAMENTALS   OF  PSYCHOLOGY 

between  the  oblique  lines  with  the  horizontal  lines  and 
really  makes  a  judgment  of  the  spaces,  although  it  is 
assumed  that  the  lines  are  being  compared.  This  is 
one  application  of  the  so-called  theory  of  confluxion  and 
contrast.     This  would  be  an  instance  of  confluxion  or 


^ I ^ 

6  1 1 

1_  e 

d 


Fig.  79.  —  Contrast  illusions.     (From  Titchener,  op.  cit.) 

of  the  tendency  to  confuse  something  in  the  surroundings 
with  the  part  of  the  figure  that  is  to  be  judged. 

The  eye-movement  theory  is  in  this  case  rather  far- 
fetched. Dawes-Hicks  found  that  the  illusion  per- 
sisted- when  the  figures  were  exposed  for  too  short  a  time 
to  permit  the  eyes  to  move.  And  while  Judd  found 
that  moving  pictures  taken  of  the  eyes  while  the  figures 
are  being  compared  showed  movements  that  in  many 


PERCEPTION  —  SPACE 


311 


instances  correspond  to  the  illusion,  he  concluded  that 
the   movements   are   due   to   the   illusion   rather   than 


Fig.  80.  —  Contrast  illusions.     (From  Titchener,  op.  cit.) 

the  illusion  due  to  the  movement.  The  perspective 
theory  serves  to  correlate  a  number  of  different  illusions 
and  may  have  some  influence,  but  is  hardly  to  be  re- 
garded as  the  only  explanation.  In  a  wide  sense,  the 
confluxion  theory  comes  to  mean  that  factors,  other  than 
those  immediately  compared,  play  a  part  in  determining 


Fig.  81.  —  lUusiftn  due  to  confluxion.     (From  Titchener,  op.  cit!) 

the  comparison,   and  in  this  form  would  include  the 
perspective  element  as  well  as  any  other  considerations 


312 


FUNDAMENTALS   OF  PSYCHOLOGY 


that  might  aid  in  controlling  the  judgment.     On  the 
whole  it  more  nearly  corresponds  to  the  facts. 

Illusions  of  size  that  illustrate  the  effect  of  contrast  are 
seen  in  the  lines  of  Figure  79  and  the  circles  of  Figure  80. 
The  distance  between  two  short  lines  seems  much  longer 
than  one  of  the  same  length  between  two  long  lines. 

Much  the  same  effect 
is  obtained  with  the 
circles.  In  Figure  81, 
the  two  circles  when 
put  together  to  form 
a  band  seem  the  one 
larger,  the  other  smaller, 
than  when  separate. 
When  together,  each 
approximates  the  size 
of  the  centre  of  the 
band  and  so  tends  to- 
wards the  average 
(confluxion).  When  a 
circle  is  surrounded  by  a  series  of  very  small  circles,  its 
size  increases  as  compared  with  the  same  circle  near  a 
single  much  larger  one  (Fig.  80). 

Angle  Illusions.  —  Illusions  of  direction  are  also 
numerous.  They  may  be  illustrated  by  the  Zollner  illu- 
sion (Fig.  82),  the  Hering  figure,  the  Wundt  figure  (Fig. 
83,  A  and  B),  and  the  Poggendorf  figure  (Fig.  84). 
The  eye-movement  theories,  the  perspective  explanation, 
and  confluxion  have  all  been  used  as  explanations.  The 
eye-movement  theory  holds  that  the  eyes  are  distracted 
by  the  cross  lines,  but  why  they  should  be  is  not  made 


Fig.  82. 


Zollner's  Illusion.     (From  Titch- 
ener,  op.  cil.) 


PERCEPTION  —  SPACE 


313 


particularly  clear.     The  perspective  theory  may  take 
two  forms.     Each  of  the  first  three  figures  may  be  seen 


pjg  83.  _  Hering's  and  Wundt's  figures.     (From 


Titchener,  op.  cit.) 


as  if  drawn  in  perspective,  and  as  the  paraUel  Unes  do 
not  converge  as  they  should  to  harmonize  with  the 
perspective,  it  is  assumed  that  they  must  diverge. 
StiU  another  appHcation  is  that  the  whole  figures  may 


314 


FUNDAMENTALS  OF  PSYCHOLOGY 


be  explained  as  due  to  the  overestimation  of  acute  angles 
and  the  underestimation  of  obtuse  angles.  It  will  be 
seen  that  this  is  what  really  happens  in  each  case.  But 
it  may  be  said  in  addition  that  the  estimation  of  the 
angles  is  made  on  the  assumption  that 
whenever  two  lines  cross  at  right 
angles  and  are  distorted  by  perspec- 
tive, the  figure  represents  two  Hnes 
crossing  at  right  angles  as  seen  with 
the  horizontal  line  in  an  oblique  plane. 
This  can  be  made  out  in  Figure  85, 
where  the  two  Hnes  can  easily  be 
imagined  to  represent  two  hnes  cross- 
ing at  right  angles.  Since  all  angles 
made  by  straight  hnes  are  likely  to 
indicate  right  angles  seen  in  perspec- 
tive, we  have  acquired  the  habit  of 
overestimating  acute  and  underesti- 
mating obtuse  angles.  The  Poggen- 
dorf  illusion  readily  falls  under  this 
explanation.  The  lines  do  not  meet 
because  each  is  turned  toward  the 
horizontal,  and  they  are  turned  to- 
ward the  horizontal  by  the  overesti- 
mation of  the  small  angles;  or  to  go  back  to  the  ex- 
planation of  that  tendency,  one  inclines  to  see  it  as  if  it 
were  really  more  nearly  perpendicular  to  the  vertical 
line. 

These  illusions,  then,  are  all  due  to  the  fact  that  in- 
terpretation tends  to  become  mixed  with  sensation  and 
that  one  cannot  keep  attention  fixed  exclusively  upon 


Fig.  84.  —  Poggen- 
dorf's  Illusion.  (From 
Titchener,  op.  cit.) 


PERCEPTION  —  SPACE  315 

the  essentials  of  the  figure  but  is  misled  by  its  surround- 
ings. Mixed  with  the  confusion  of  part  with  the  whole 
is  always  the  tendency  to  see  what  the  figure  means 
rather  than  the  figure  itself,  and  to  believe  that  it  means 
something  different  from  what  is  actually  represented. 
The  various  special  theories,  perspective,  confusion,  or 


Fig.  85.  —  Hering's  angle  illusions.  Careful  observation  shows  that  any  of 
the  oblique  lines  may  be  interpreted  as  crossing  in  some  other  than  the  plane 
of  the  other  line.     (From  Titchener,  op.  cit.) 

confluxion,  even  eye  movements,  are  but  special  forms 
of  this  general  tendency. 

General  Theories  of  Space  Perception.  —  A  more  ab- 
stract problem  naturally  arises  at  the  end  of  a  statement 
of  the  particular  facts  of  space  perception,  the  question 
what  is  space  itself.  Two  schools  have  contended  over 
this  question  since  the  beginnings  of  modern  philosophy. 
One,  the  nativistic  school,  insists  that  the  capacity  to 
appreciate  space  is  born  with  us  and  may  be  used  without 


3i6 


FUNDAMENTALS   OF  PSYCHOLOGY 


preliminary  practice.  It  may  be  dependent  upon  in- 
herited characteristics  of  our  nervous  system,  or  may  be 
an  original  mental  activity.  The  other  school,  the 
empirical,  asserts  that  space  is  developed  through 
experience,  —  must  be  in  some  way  derived  from  the 
conditions  of  perception.  For  the  first,  space  offers 
no  problems ;  it  is  appreciated  at  once,  as  color  is  appre- 
ciated. For  the  empiricist  it  is  neces- 
sary to  discover  the  components  of 
the  space  idea  and  also  to  determine 
how  a  particular  space  idea  is  sug- 
gested. The  concrete  evidence  for 
neither  position  is  very  definite.  The 
empiricists  point  to  the  numerous 
cases  of  error  in  judgment,  and  the 
cases  in  which  appreciation  of  space 
may  be  shown  to  depend  upon  defi- 
nite sensations  and  particular  associ- 
ations. The  nativist  contents  himself  with  the  state- 
ment that  the  factors  that  the  empiricist  asserts  compose 
space  are  altogether  different  from  space  as  we  know  it, 
and  also  that  it  is  inconceivable  that  space  can  be  derived 
from  anything  not  itself  spatial. 

The  Space  Discrimination  of  Those  Born  Blind.  — 
The  problem  cannot  ordinarily  be  approached  directly, 
since  the  child  has  already  developed  his  notion  of  soace 
before  he  is  able  to  tell  us  about  it,  and  adults  have 
long  since  forgotten  what  their  fir^t  experiences  were 
like  and  how  they  developed  spatial  ideas.  Already 
in  the  seventeenth  century,  Locke  suggested  that  if 
one  could  find  a  man  who^iad  been  born  blind  and 


Fig.  86.  — The  trans- 
formation of  right  an- 
gles in  natural  objects 
seen  in  perspective. 


PERCEPTION  —  SPACE  3 1 7 

recovered  his  sight  after  he  became  able  to  describe 
his  experiences,  it  would  be  possible  to  say  how  much 
of  space  perception  was  innate  and,  if  not  innate,  how  it 
was  acquired.  Since  then  a  fair  number  of  cases  of  this 
sort  have  been  observed.  The  lens  of  the  eye  is  oc- 
casionally opaque  from  birth  and  may  be  removed  by 
an  operation,  and  the  patient  may  be  made  to  see.  There 
is  no  great  agreement  as  to  what  the  patient  can  see,  but 
the  following  statements  seem  to  be  in  harmony  with 
most  results.  The  shape  of  objects  is  not  recognized 
at  all.  One  patient  could  not  tell  a  square  from  a  circle 
until  he  had  had  a  chance  to  touch  each.  The  field  of 
vision  is  described  as  a  confused  mass  in  which  everything 
seems  to  be  in  irregular  movement.  Some  patients 
seem  to  notice  the  difference  between  geometrical 
figures  when  they  cannot  say  in  what  that  difference 
consists.  One,  after  being  told  what  an  angle  was, 
could  count  the  angles  on  a  figure  and  thus  distinguish  a 
triangle  from  a  square,  but  for  some  time  afterwards  was 
not  able  to  distinguish  without  this  counting.  The  per- 
ception of  distance  was  always  defective.  Objects  seemed 
in  most  cases  to  touch  the  eye  and  in  no  case  were  they 
projected  beyond  the  reach  of  the  patient.  There  is 
practically  no  appreciation  of  depth.  Neither  school 
is  altogether  con\dnced  of  the  falsity  of  its  own  position 
by  the  e\'idence.  The  nativist  argues  that  the  patient 
sees  so  little  because  he  transfers  the  associations  de- 
veloped by  touch  to  sight.  The  patient  thinks  objects 
must  touch  his  eyes  because  they  touch  his  skin.  The 
empiricist,  on  the  contrary,  argues  that  the  patient  would 
see  nothing  were  it  not  for  this  same  earher  experience^ 


3l8  FUNDAMENTALS   OF  PSYCHOLOGY 

that  interpretation  from  tactual  experiences  and  from 
the  light  that  comes  through  the  lenses  before  the  opera- 
tion makes  possible  even  the  imperfect  spatial  judgments 
that  are  made. 

The  attempts  made  by  the  empiricist  to  explain  or 
analyze  the  spatial  experience  have  for  the  most  part 
consisted  in  reducing  the  various  forms  into  some  single 
one.  Movements  or  memories  of  movements  are  most 
frequently  asserted  to  constitute  true  space.  Double 
images,  on  the  theory,  give  an  idea  of  depth  because 
they  call  up  the  memories  of  old  movements  of  con- 
vergence or  of  the  reaching  movements  required  to  ob- 
tain the  object.  That  such  transfers  from  one  sense  to 
another  do  take  place  is  readily  observed.  Most  persons 
use  a  visual  space,  although  a  motor-minded  individual 
may  translate  visual  and  tactual  distances  into  kinaes- 
thetic  terms.  But,  after  all,  translation  from  one  space 
to  another  does  not  solve  the  problem  of  space.  No 
one  sense  gives  a  more  direct  and  intuitive  knowledge 
of  space  than  any  other.  Vision  is  probably  more  deli- 
cate in  its  appreciation,  while  movement  demands  an 
accuracy  in  space  estimates  to  be  adequate,  but  it  can- 
not be  said  that  the  accuracy  of  the  one  or  the  needs  of 
the  other  constitute  it  the  intuitive  space  sense. 

We  may  reduce  the  problem  of  the  origin  of  space  to 
its  lowest  terms  if  we  see  that  there  are  three  essential 
elements  in  the  spatial  experience.  These  are  the  sensa- 
tion or  sensory  cue,  the  idea  or  notion  of  space,  and  the 
association  between  them.  The  sensory  cue  always  is 
present  before  the  idea  can  be  suggested.  Contact  on 
a  spot  calls  up  the  idea  of  position;  double  images, 


PERCEPTION  —  SPACE  3 1 9 

strains  of  accommodation,  and  convergence  suggest 
the  distance.  The  question  whether  it  is  innate  or 
derived  from  experience  may  be  considered  for  each 
separately.  We  may  assert  at  once  that  the  connection 
is  derived  through  experience.  Illusions  show  that  the 
associates  may  be  misplaced  —  the  wrong  idea  may  be 
called  up  by  any  cue,  —  and  an  innate  capacity  to  make 
mistakes  is  not  desired  by  the  most  ardent  supporters  of 
that  theory. 

The  most  that  can  be  innate  is  the  stimulus  or  cue  and 
the  idea  of  space  that  it  calls  out.  That  the  exciting  cause 
is  a  bare  sensation  or  sensory  stimulus  which  depends  upon 
the  physical  structure  of  the  sense  organ  or  the  nervous 
connections  and  in  this  sense  is  innate,  no  one  will  deny. 
The  case  for  the  idea  is  not  so  clear.  Whether  this  be 
innate  or  derived  is  the  real  crux  of  the  problem.  The 
argument  that  it  is  derived  must  give  over  any  attempt 
to  reduce  it  to  a  single  element  or  even  to  a  combination  of 
different  elements  that  preserve  their  original  character. 
Space  cannot  be  movement,  it  cannot  be  sight  or  touch. 
Judd  has  suggested  that  it  is  not  a  movement  but  an 
organized  system  of  movements  in  which  the  various  con- 
tradictions have  been  removed  and  suited  to  all  possible 
occasions  for  action.  If  we  accept  this  statement  as 
far  as  it  goes,  we  must  add  to  it  that  space  is  an  organiza- 
tion of  experience  as  a  whole,  sensory  as  well  as  motor, 
and  that  there  results  from  it  not  movement,  but  a  con- 
cept or  notion  which  not  merely  prepares  for  action 
but  makes  it  possible  to  represent  all  spatial  experiences 
consistently  and  harmoniously.  We  may  use  it  for  our 
estimates  of  space,  as  well  as  in  the  control  of  move- 


320  FUNDAMENTALS    OF   PSYCHOLOGY 

ments,  —  for  the  combinations  of  the  mathematician  as 
well  as  for  the  actual  structures  of  the  engineer.  What 
the  actual  content  of  this  idea  is  cannot  be  asserted. 
Like  most  concepts,  it  is  more  important  for  the  things 
it  represents  than  for  itself.  It  probably  varies  in 
many  respects  from  individual  to  indi\dduaL  It  is 
certainly  more  highly  developed  for  the  mathematician 
than  for  the  common  man,  and  more  highly  developed 
for  the  adult  than  for  the  child,  for  the  civiHzed  man  than 
for  the  savage.  The  process  of  development  has  prob- 
ably been  to  accept  some  simple  idea  or  even  sensation 
and  to  use  it  until  contradictions  appear.  These  are 
obviated  by  changing  the  notion  until  something  that 
avoids  the  difficulties  is  hit  upon,  and  this  is  again 
changed  as  occasion  arises.  The  concept  always  grows 
out  of  practical  needs,  whether  sensory  or  motor.  Thus 
images  on  the  retina  are  given  a  size  that  can  be  most 
readily  fitted  into  our  conception  of  the  field  of  vision 
as  a  whole.  Small  objects  are  usually  seen  as  if  they 
were  at  about  arms'  length  or  where  they  can  be  easily 
manipulated,  houses  at  a  distance  that  gives  us  a  good 
view  of  them;  and  in  thought  these  various  typical 
distances  or  sizes  are  used  in  place  of  the  sizes  of  the 
images  on  the  retina.  They  are  what  are  called  the  real 
sizes  of  the  objects.  Similar  notions  develop  for  posi- 
tion, for  extent,  and  for  depth.  They  are  changed  and 
adjusted  until  they  satisfy  the  conditions  of  movement, 
of  sight  and  touch,  and  of  the  practical  and  theoretical 
needs  of  every  sort.  In  the  final  concept  little  if  any 
trace  of  the  particular  ideas  need  be  left,  certainly 
nothing  that  can  be  analyzed  out  of  the  concept  by  direct 


PERCEPTION  —  SPACE  32 1 

introspection.  It  represents  the  various  experiences 
as  corrected  by  different  tests,  but  it  is  not  compounded 
out  of  them.  Our  choice  as  to  the  real  nature  of  space 
lies  between  these  alternatives  of  assuming  on  the  one 
hand  that  it  is  a  concept  that  has  developed  out  of 
experience  by  innumerable  trials  that  finally  give  rise 
to  a  system  of  ideas  that  will  satisfactorily  represent 
space,  and  of  assuming,  on  the  other  hand,  the  nati\dst 
position,  that  space  is  given  once  and  for  all  and  that 
we  certainly  cannot  explain  it.  We  can  at  most  watch 
its  development.  The  former  seems  to  the. writer  to 
offer  the  possibiHty  of  a  real  explanation,  the  latter  at 
most  gives  up  the  question  as  insoluble. 

REFERENCES 

jAiiES  :  Principles  of  Psycholog}',  vol.  11,  pp.  134-282. 
Ladd-Wood WORTH :    Principles  of  Physiological  Psychology,  pp 

380-469. 
WiTASEK :  Raum-Wahrnehmung. 


CHAPTER  IX 

PERCEPTION  — VISUAL    MOVEMENT,    OF   TIME,   AND 
THE   GENERAL  LAWS   OF   PERCEPTION 

Visual    Perception    of    Movement.  —  How    the    eye 

appreciates  movement  is  a  problem  closely  related  to 
the  perception  of  space ;  in  many  ways  it  is  inter- 
mediate between  the  perception  of  space  and  of  time. 
Two  forms  of  movement  must  be  distinguished,  one  in 
which  the  movement  can  be  actually  seen,  and  a  second 
in  which  movements  are  so  slow  that  one  infers  that 
the  object  has  moved  from  the  fact  that  its  position 
changes  between  two  observations.  The  movements 
of  a  meteor  belong  in  the  first  class,  that  of  the  sun  in 
the  second.  The  slowest  rate  that  can  be  really  seen 
is  one  angular  minute  per  second.  Movements  may 
also  be  too  fast  to  be  seen  directly.  An  electric  spark 
moving  more  than  15''  in  a  thousandth  of  a  second 
cannot  be  seen  to  move.  Nothing  more  is  seen  than 
the  path.  How  we  perceive  the  movement  of  objects 
at  the  intermediate  rates  offers  a  definite  problem,  but 
one  concerning  which  theories  are  in  conflict.  Three 
different  theories  may  be  mentioned.  The  first  holds 
that  the  eye  follows  the  moving  object,  and  that  appre- 
ciation of  the  movement  of  the  eye  gives  also  a  knowl- 
edge of  the  movement  of  the  object.  This  theory  is 
very  direct  but  depends  for  its  acceptance  upon  proof 

322 


VISUAL    PERCEPTION    OF    MOVEMENT  323 

of  ability  to  appreciate  the  movement  of  the  eye  muscles. 
Recently,  various  bits  of  evidence  indicate  that  move- 
ments of  the  eye  muscles  are  much  less  accurately 
known  than  has  been  sometimes  assumed.  In  the  first 
place,  there  is  little  accuracy  in  estimating  the  move- 
ment of  an  object  when  it  stands  alone  in  the  field  of 
vision.  A  faint  light  mo\dng  in  the  dark  may  seem  to 
move  much  more  slowly  than  it  really  does,  and  on  the 
contrary  a  stationary  light  may,  under  those  circum- 
stances, seem  to  be  mo\ing.  If  two  faint  lights  are 
attached  to  the  ends  of  a  rod  swinging  from  a  point  near 
its  middle,  either  light  may  seem  to  move  while  the 
other  is  stationary,  or  the  motion  may  be  di\aded  be- 
tween them  in  any  proportion.  When  only  two  lights 
are  in  the  field,  one  sees  the  relative  but  not  the  absolute 
motion.  \\Tien  stationary  objects  are  in  the  field,  it 
seems  that  the  movement  of  objects  is  determined  by 
their  relation  to  the  fixed  objects  in  the  field  of  \dew, 
rather  than  by  following  the  object  with  the  eye  and 
appreciating  the  movement  through  the  contraction  of 
the  muscles. 

The  After-image  Theory.  —  Stern,  among  many  other 
writers,  has  suggested  a  second  theory, —  that  movements 
are  appreciated  through  the  after-images  that  the  mo\dng 
object  leaves  upon  the  retina.  Watch  any  object  in 
fairly  rapid  motion  and  you  will  notice  that  it  leaves 
a  trail  of  after-images  as  it  moves  and  that  its  course 
can  be  distinctly  made  out  for  a  few  moments  by  means 
of  this  trail.  The  motion  of  the  moving  picture  is  due, 
on  this  theory,  to  the  fact  that  the  separate  pictures 
of  the  object  also  leave  a  line  of  after-images  and  that 


324  FUNDAMENTALS    OF   PSYCHOLOGY 

these  are  interpreted  to  mean  motion.  The  motion  seems 
continuous  if  the  separate  images  succeed  each  other 
with  an  interval  of  no  more  than  fifteen  thousandths 
of  a  second,  a  rate  a  little  higher  than  that  ordinarily 
used  in  exhibitions,  which  is  fifty  per  second.  If  this 
theory  be  applied  to  explain  the  differences  between 
the  three  kinds  of  motion,  movements  too  slow  to  be 
seen  must  leave  no  after-image  that  can  be  noticed, 
while  in  movements  too  fast  to  be  seen,  no  distinction 
can  be  made  between  the  after-image  and  the  primary 
stimulation.  The  whole  course  is  of  approximately  the 
same  intensity.  The  after-images  also  give  a  means  of 
determining  the  course  of  the  motion.  They  are  more 
intense  near  the  stimulus  and  grow  gradually  fainter 
the  greater  the  distance  from  it.  After-images,  then,  are 
interpreted  as  motion,  and  the  direction  of  the  motion 
is  assumed  to  be  from  faint  to  vivid  images. 

After-images  of  Movement.  —  That  motion  itself 
has  an  after-image  is  an  important  fact  for  the  theories 
of  movement,  and  its  study  has  contributed  much  to  the 
explanation  of  movement  in  general.  If  one  look  for 
several  seconds  at  any  moving  surface,  the  paper  on  a 
kymograph,  a  stream,  or  at  a  revolving  spiral,  and  then 
look  away  at  a  stationary  surface,  there  will  seem  to 
be  a  movement  in  the  opposite  direction.  Two  explana- 
tions of  this  phenomenon  have  been  offered ;  that  it  is 
due  to  the  reversal  of  the  after-image,  and  that  it  is  due 
to  an  actual  displacement  of  retinal  elements  by  the 
motion,  followed  by  their  return  to  the  original  position 
when  the  movement  ceases.  Visual  after-images  change 
from  positive   to  negative   shortly  after   the   stimulus 


VISUAL    PERCEPTION    OF    MOVEMENT  325 

is  removed,  as  will  be  remembered  from  an  earlier  chapter. 
If  in  the  original  motion  the  after-images  near  the  object 
are  dark  and  shade  off  gradually,  in  the  negative  after- 
image the  dark  portion  will  become  bright,  shading 
off  to  a  darker  region.  A  negative  after-image  of 
brightness  would  give  an  apparent  reversal  of  the 
movement. 

The  Theory  of  Retinal  Streaming.  —  That  the  per- 
ception of  movement  and  the  reversal  of  direction  in  the 
after-image  are  due  to  actual  movement  of  elements 
in  the  retina  has  been  asserted  for  some  time  and  has 
been  strongly  supported  recently  by  Ferree  and  Hunter. 
This  is  our  third  theory  of  the  perception  of  movement. 
The  evidence  in  its  favor  is  the  great  vividness  and  per- 
sistence of  the  sensory'  processes,  particularly  in  the 
after-image  of  movement.  These  observers  assert  that 
when  the  after-image  of  motion  is  well  developed,  there 
seems  to  be  a  veil  of  objects  streaming  over  any  surface 
looked  at,  and  that  it  would  be  impossible  for  after- 
images or  any  of  the  other  factors  suggested  to  persist 
long  enough  or  to  be  sufficiently  realistic  to  account 
for  the  effect  noticed.  On  the  other  hand,  they  admit 
that  what  we  know  of  the  retinal  structure  gives  no 
evidence  in  favor  of  an  actual  movement  of  its  elements. 
Altogether  the  after-image  theory  seems  more  plaus- 
ible. After-images  are  known  to  exist  and  must  play 
a  part  in  the  perception  of  motion.  The  only  question 
is  whether  they  account  for  all  of  the  observed  phenom- 
ena. We  may  at  least  accept  it  as  the  most  probable 
theory  at  present  for  the  explanation  of  all  perception 
of  movement. 


326  FUNDAMENTALS   OF   PSYCHOLOGY 

Granting  that  the  problem  of  how  we  see  movement 
at  all  is  settled,  it  is  still  necessary  to  consider  how  we 
distinguish  between  possible  interpretations  in  actual 
movements.  Many  of  the  phenomena  may  be  the 
result  of  several  different  conditions  in  the  outer  world. 
Either  the  eye  or  the  field  of  vision  may  be  in  motion 
when  many  objects  are  leaving  after-images.  We  may 
distinguish  three  conditions  of  motion  if  we  consider 
only  the  movements  of  objects  and  of  the  eyes.  The 
eye  may  be  stationary  and  one  object  in  motion;  the 
eye  may  be  in  motion,  following  one  object,  perhaps, 
while  the  rest  of  the  field  is  statioilary ;  or,  finally, 
the  eye  may  be  following  one  object  while  other  objects 
are  moving  in  different  directions  or  at  different  rates. 
The  first  case  has  been  discussed  above.  In  the  second 
case  one  would  have  a  clear  image  of  the  object  that 
was  pursued  by  the  eye,  while  all  other  objects  would 
be  seen  in  blurred  images  or  would  be  leaving  after- 
images. Here  we  must  explain  how  we  know  that  the 
eye  is  moving.  This  might  be,  either  through  the  sensa- 
tions from  the  eye  muscles,  or  by  the  after-images  or  other 
signs  of  movement  developed  on  the  retina  by  stationary 
objects.  The  clear  image  of  the  object  in  flight  would 
show  that  it  was  being  properly  followed,  while  the 
after-images  of  all  other  objects  serve  as  an  indication 
of  the  movement  of  the  eye.  Still  more  complicated, 
but  nevertheless  capable  of  explanation  along  the  same 
lines,  is  the  problem  offered  when  the  object  and  eye 
are  in  motion  in  different  directions  or  at  different 
rates.  Here  the  total  estimate  is  based  on  a  compari- 
son of  the  movement  of  the  eye  with  the  displacement 


RHYTHM  327 

of  the  image.  In  each  of  these  cases  much  depends  upon 
the  estimate  of  the  probability  of  movement.  Even 
when  it  is  a  question  whether  the  motion  is  of  the  external 
object  or  of  the  observer,  interpretation  plays  a  large 
part.  If  one  stands  on  a  bridge  over  a  rapidly  running 
stream,  it  is  quite  easy  to  ascribe  the  motion  to  the  bridge. 
The  probabilities  in  the  light  of  frequency  of  occurrence 
are  that  a  small  object  like  a  bridge  will  be  in  motion 
rather  than  the  larger  river.  Similarly,  when  you  are 
on  one  of  two  trains  standing  in  a  station,  and  one 
starts,  motion  is  ascribed  to  one  or  the  other  in  accord- 
ance with  your  expectations.  Not  merely  the  sensory 
elements  that  give  the  perception  of  motion  must  be 
taken  into  account,  but  also  the  estimation  through  early 
experience  of  the  probability  that  the  object  is  or  is  not 
likely  to  move. 

REFERENCES 

Ferree  :     The    Streaming    Phenomenon,   Amer.    Jour.    Psych., 

vol.  19. 
Hunter:    Retinal  Factors  in  Visual  After-^Iovement,  Psychol. 

Rev.,  vol.  22,  p.  479. 
Wom^GEMUTH:    On  the  After-Effects   of   Visual  ^lotion,    Brit. 

Journal  of  Psychology,  ^Monograph  Suppl.  I. 

Rhythm 

Most  series  of  excitations  which  repeat  themselves 
at  short  intervals  tend  to  fall  into  rhythm.  Rhythm 
needs  no  description,  and  one  could  not  be  given  if 
demanded.  Two  factors  may  be  distinguished  in 
rhythm,  the  grouping  of  the  single  elements  into  units, 
and  the  accenting  or  emphasizing  of  one  or  more  of  the 


328  .  FUNDAMENTALS   OF   PSYCHOLOGY 

units.  Auditory  and  kinaesthetic  impressions  show 
rhythm  most  easily,  tactual  and  visual,  not  so  markedly. 
The  accentuation  in  rhythm  may  be  produced  in  a 
number  of  different  ways  and  still  give  the  same  effect. 
It  can  be  given  subjectively  as  well  as  objectively.  If 
one  listen  to  the  ticking  of  a  clock  or  the  beats  of  a 
metronome,  it  will  be  noticed  that  they  tend  to  form 
units,  and  that  the  character  of  the  unit,  the  sound  that 
is  accented,  will  vary  from  time  to  time  and,  within 
limits,  can  be  changed  at  will.  Objectively,  it  is  possi- 
ble to  emphasize  one  unit  in  the  measure,  either  by  in- 
creasing the  intensity  of  the  note  to  be  accented,  or  by 
increasing  the  length  of  the  note.  This  is  evidenced  by 
a  comparison  of  ancient  with  modern  verse.  While  the 
former  produced  its  rhythmic  effect  by  lengthening  the 
syllable,  English  poetry  obtains  the  same  effect  by  in- 
creasing the  intensity  of  the  syllable.  A  similar  differ- 
ence in  the  way  of  producing  effects  can  be  seen  in  music 
between  the  organ  and  the  piano.  On  the  organ  the 
intensity  is  constant,  rhythm  is  obtained  by  increasing 
the  duration  of  a  tone,  while  on  the  piano,  accent  is  given 
by  increasing  the  intensity  of  the  note.  The  rhythm  is 
the  same  in  both  cases.  In  fact,  men  who  have  played 
the  organ  for  years  often  do  not  notice  either  the  differ- 
ence in  the  effect  or  in  the  way  in  which  it  is  produced. 
Not  only  may  accent  be  given  by  changing  the  character 
of  the  note,  but  also  by  changing  the  intervals  between 
the  notes.  In  a  measure  of  three  notes  of  the  same 
intensity  and  duration,  if  the  first  interval  be  increased, 
the  first  note  will  be  accented ;  if  the  second  interval 
be  increased,  the  last  note  will  be  accented. 


RHYTHM  329 

The  way  in  which  groups  are  formed  in  regularly 
recurrent  sensations  may  also  be  reduced  to  certain  laws. 
The  more  rapid  the  rate  of  succession,  the  greater  the 
number  that  may  be  brought  into  a  single  unit.  In 
very  rapid  beats  of  the  metronome,  two  hundred  per 
minute  or  so,  it  is  possible  to  combine  as  many  as  eight 
beats  in  a  single  unit.  The  size  of  the  unit  may  be  varied 
at  -^all,  within  limits.  When  they  are  sixty  or  less 
per  minute,  it  is  with  difficulty  that  two  may  be  grouped. 
In  general,  Woodrow^  found  that  in  a  series  of  tones 
separated  by  equal  intervals  in  which  every  other  note 
or  every  third  was  more  intense,  the  group  would  begin 
with  the  more  intense  tone.  WTien  intensities  were 
equal  but  alternate  notes  were  longer,  the  longer  note 
would  start  the  measure.  The  grouping  and  the 
accent  depend  upon  both  objective  and  subjective 
factors. 

The  Theories  of  Rhythm.  —  Two  theories  to  explain 
these  various  facts  of  rhythm  are  at  present  current. 
One  is  that  rhythm  has  a  motor  origin,  that  the  impulse 
to  beat  time  is  universal,  and  that  any  external  series 
that  will  call  out  this  tendency  produces  the  rhythm. 
Genetically,  it  is  argued  that  rhythmic  movements 
are  inseparable  from  bodily  activity,  that  the  movements 
in  physical  labor  came  to  take  on  a  rhythmic  form  and 
this  may  have  been  transformed  into  the  dance  which  in 
primitive  races  is  frequently  derived  from  the  daily 
work,  and  that  it  then  was  introduced  into  music  and 
reached  its  present  degree  of  complexity.  The  other, 
an  attention  theory,  develops  from  the  fact  that  most 
of  the  factors  that  induce  accentuation  also  give  rise 


330  FUNDAMENTALS   OF   PSYCHOLOGY 

to  attention.  Both  intensity  and  length  of  stimulus 
were  found  among  the  objective  conditions  of  attention. 
More  striking  is  the  evidence  from  the  effects  of  the 
preceding  and  succeeding  interval.  A  period  of  expecta- 
tion is  an  important  factor  in  arousing  attention.  Where 
a  note  in  the  rhythmic  group  has  been  preceded  by  an 
interval,  expectation  increases  regularly  during  the 
preliminary  wait ;  and  when  the  stimulus  finally  makes 
its  appearance,  it  is  more  fully  attended  to  and  seems 
more  intense  than  impressions  that  have  been  preceded 
by  the  shorter  interval.  Less  obvious  is  the  explana- 
tion of  the  effect  when  a  longer  interval  succeeds  the 
stimulus.  This  seems  to  offer  opportunity  for  full  at- 
tention to  the  effect  of  the  stimulus  after  it  has  stopped, 
and  this  is  supposed  also  to  increase  its  apparent  inten- 
sity. It  seems  probable,  from  observation  and  particu- 
larly from  the  fact  that  an  interval  affects  the  accent 
of  the  note  that  preceded,  that  the  appreciation  of  the 
rhythmic  unit  takes  place  at  the  end  of  the  measure. 
The  unit  is  heard  as  a  whole  at  the  moment  it  is  com- 
pleted rather  than  bit  by  bit  as  each  impression  comes 
to  consciousness.  The  attention  theory,  then,  would 
hold  that  rhythm  is  induced  by  any  circumstance  that 
makes  some  one  or  more  elements  in  the  series  of  tones 
occupy  a  more  important  place  in  consciousness  than 
the  others,  and  that  the  whole  group  becomes  a  unit  for 
attention.  While  the  attention  theory  has  some  advan- 
tages in  explaining  why  the  emphasis  comes  as  it  does, 
it  seems  probable  that  a  considerable  portion  of  the 
sensory  content  of  the  rhythm  is  suppHed  by  the  motor 
contractions  which  may  come  as  a  result  of  the  subjective 


PERCEPTION    OF    TIME  33 1 

accentuation.  A  good  case  can  be  made  for  either 
theory,  and  they  are  not  at  all  contradictory  or  out  of 
harmony  one  with  the  other. 


The  Perception  of  Time 

Time  offers  many  of  the  same  problems  as  space. 
It,  too,  is  a  universal  characteristic  of  all  our  experience, 
and  there  has  been  the  same  discussion  as  to  whether 
it  has  real  existence  or  is  merely  subjective.  As  with 
space,  we  may  ask  how  short  a  time  can  be  noticed,  and 
how  we  appreciate  longer  intervals.  The  traditional 
question,  how  short  a  time  may  be  experienced,  receives 
a  different  answer  for  each  of  the  senses  and  combina- 
tions of  senses.  It  is  much  shorter  for  hearing  (.002) 
than  for  sight  (.044)  and  may  rise  to  0.16  second  when 
one  stimulus  is  given  by  sight,  the  other  by  the  ear. 
WTien  one  turns  to  a  study  of  the  longer  times,  it  is 
found  that  the  nature  of  the  estimation  of  time  and 
even  the  way  time  feels  varies  greatly  with  the  duration 
of  the  intervals  involved.  If  one  is  asked  to  listen  to 
times  of  different  length,  certain  are  at  once  pronounced 
very  short,  too  short  to  be  perceived  with  comfort, 
others  as  too  long  to  be  comfortably  appreciated.  Times 
under  5500-  (o-  means  thousandths  of  a  second)  seem  too 
short,  are  hurried,  and  not  adequately  comprehended. 
On  the  other  hand,  times  over  about  18000-  seem  very 
long,  and  it  is  with  difficulty  that  they  can  be  brought 
within  the  span  of  comprehension.  At  about  four 
seconds,  it  is  no  longer  possible  to  bring  the  events 
within  a  single  compass ;    one  reaches  the  limit  of  a 


332  FUNDAMENTALS    OF   PSYCHOLOGY 

single  span  of  time  so  far  as  it  can  be  experienced.  It 
should  be  noted  that  this  is  also  approximately  the 
length  of  the  primary  memory.  Within  this  period 
events  may  be  held  in  a  single  span  of  memory,  and 
the  memory  image  can  be  used  with  the  same  care 
and  certainty  as  a  sensation.  It  is  by  virtue  of  this 
fact  that  it  is  said  to  constitute  the  immediately  experi- 
enced present. 

The  Different  Ways  of  Perceiving  Time.  —  The  point 
of  division  between  the  hurried  and  the  comfortable  time 
is  of  interest  for  another  reason.  It  is  found  that  if 
one  attempts  to  compare  times  under  0.6-0.75  second, 
there  is  always  a  tendency  to  overestimate  the  first, 
while  similar  comparisons  of  times,  greater  than  this 
indifference  time,  lead  to  the  underestimation  of  the 
first.  This  time  approximately  coincides  with  the  point 
of  division  between  the  times  felt  as  very  short  and  those 
which  seem  of  moderate  duration,  and  furnishes  addi- 
tional evidence  that  there  is  a  real  difference  in  the 
means  of  estimating  times  above  and  below.  Some 
Hght  may  be  thrown  upon  the  conditions  of  the  percep- 
tion of  time  by  a  study  of  the  factors  that  influence 
the  comparison  of  intervals.  First,  anything  that  influ- 
ences expectation  plays  some  part.  Thus,  if  sounds 
are  separated  by  equal  intervals  and  every  other  note  is 
more  intense,  the  interval  that  precedes  the  more  intense 
sound  will  seem  to  be  lengthened.  This  has  been  ex- 
plained as  due  to  the  surprise  induced  by  the  strong 
tone,  which  increases  the  strain  ascribed  to  the  preceding 
interval. 

Another  factor  that  influences  the  appreciation  of  time 


PERCEPTION    OF    TIME  333 

is  the  way  the  interval  is  filled.  With  short  times 
it  is  found  that  filled  time  seems  longer  than  the  same 
length  of  time  limited  by  two  sounds  but  otherwise 
empty.  If  the  timxe  be  longer  and  one  be  permitted 
to  read  during  one  period  and  to  do  nothing  during 
the  other,  the  filled  time  seems  shorter  than  the  empty. 
The  probable  explanation  of  the  latter  difference  is  to 
be  found  in  the  fact  that  the  empty  time  is  really  filled 
by  noticing  strains  and  other  internal  sensations,  while, 
during  the  time  occupied  in  reading,  these  strains  are 
not  present.  One  forgets  one's  self  and  the  passage 
of  time  in  the  interesting  event.  For  longer  times  the 
filling  seems  to  have  a  markedly  different  effect  accord- 
ing as  the  time  is  regarded  as  it  is  being  lived  through, 
or  as  it  is  viewed  in  retrospect.  While  passing,  time 
in  which  one  is  occupied  fully  and  during  which  much 
of  importance  is  happening  seems  short,  but  when  viewed 
in  retrospect  it  seems  long.  Em_pty  time,  on  the  other 
hand,  seems  long  in  the  passing  but  short  in  retrospect. 
During  convalescence  from  a  long  illness  the  days  drag 
interminably,  but  later  the  period  seems  inappreciable. 
Theories  of  Time  Perception.  —  Attempts  at  a  theory 
must  take  all  of  these  facts  into  consideration  and. 
we  must  distinguish  three  ways  of  appreciating  time. 
First  are  the  very  short  intervals,  those  under  600-7000", 
below  the  indifference  period.  These,  it  has  been  sug- 
gested, are  appreciated  in  terms  of  rhythm,  since  under 
that  limit  stimuli  may  be  easily  grouped  into  rhythmic 
wholes.  The  intervals  are  too  short  to  be  appreciated 
for  themselves,  they  cannot  be  attended  to,  and  so  do 
not  reach  their  full  development.     From  600  or   yooo" 


334  FUNDAMENTALS   OF  PSYCHOLOGY 

up  to  about  two  to  four  seconds  is  real  time.  This 
is  apparently  appreciated  in  terms  of  internal  experi- 
ences, expectation  processes,  and  other  more  definitely 
kinaesthetic  sensations.  The  length  of  the  time  is 
estimated  in  terms  of  the  intensity  of  the  strains.  Short 
times  give  them  no  chance  to  become  strong,  but  their 
strength  grows  with  the  longer  times.  Strains  of  the 
muscles  that  accompany  attention,  strains  of  expecta- 
tion, even  strains  that  come  with  respiration  or  with 
holding  the  breath,  have  been  asserted  to  form  the  basis 
of  the  appreciation  of  the  passage  of  time.  The  influ- 
ence of  the  strength  of  the  limiting  stimuli  would  sug- 
gest the  importance  of  the  strains  of  attention  and  their 
relaxation  in  the  estimation  of  time,  as  would  the  effect 
of  events  that  form  the  content  of  time  in  determining 
the  apparent  length.  When  the  interval  is  empty,  atten- 
tion would  be  more  fully  attracted  to  the  passage  of 
time,  the  strains  would  be  more  pronounced,  and  the 
time  seem  longer.  In  the  same  way  with  longer  intervals 
when  there  is  nothing  to  do,  the  strains  of  expectation 
occupy  consciousness  and  time  seems  long,  while,  when 
one  is  busy,  attention  is  otherwise  occupied  and  there  is 
constant  change,  constant  relaxation,  the  strains  never 
rise  to  great  intensities,  and  in  consequence  one  is  not 
impressed  with  the  fact  that  time  is  passing. 

Times  longer  than  from  two  to  four  seconds  are  appar- 
ently not  directly  experienced  in  the  passing,  but  are 
only  experienced  as  past.  They  fall  outside  of  the 
present,  are  constituted  for  the  most  part  by  memories 
of  past  events  revived  in  the  present.  They  are  es- 
timated in  terms  of  the  events  that  have  happened  in 


PERCEPTION    OF    TIME  335 

them,  in  terms  of  their  filling.  In  this  they  differ  alto- 
gether from  the  shorter  intervals  that  may  be  directly 
appreciated,  and  in  consequence  show  the  reverse  illu- 
sions. Thus,  times  that  are  filled  with  interesting  events 
seem  long  when  they  are  looked  back  upon,  although 
they  seem  short  in  passing ;  while  times  in  which  noth- 
ing happens  seem  short  in  retrospect,  although  extremely 
long  in  their  passage.  It  is  this  that  explains  the  seem- 
ing decrease  in  the  length  of  the  days  and  weeks  with 
advancing  years.  WTien  young,  all  is  interesting  from 
its  newness,  and  is  always  attended  to ;  as  time  goes 
on,  nearly  everything  becomes  famiHar  and  receives 
less  and  less  attention,  and  so  less  and  less  is  remembered 
in  retrospect.  In  general,  times  depend  upon  an  appre- 
ciation of  the  filling.  Very  short  times  are  apparently 
known  from  rhythm,  longer  times  from  the  physiological 
processes,  contractions  and  what  not,  that  give  the 
feeling  of  expectation  and  strain ;  while  longer  intervals, 
from  two  to  four  seconds,  are  appreciated  in  terms  of 
the  events  that  happen  in  them. 

REFERENCES 

Ladd-Woodv/orth  :   chaps,  ii,  iv-v. 

Myers  :  Experimental  Psychology,  chaps,  xx-xxiii. 

Titchener:  Textbook,  pp.  303-373. 

James  :  Principles,  vol.  i,  chap.  xv. 

Benussi  :  Psychologie  der  Zeitauffassung. 

The  General  Laws  of  Perception 

While  space  and  time  may  be  treated  separately,  since 
practically  all  perceptions  imply  them  and  they  are 
considered   to   have   an   existence   independent   of   the 


336  FUNDAMENTALS   OF  PSYCHOLOGY 

objects  found  in  them,  certain  laws  of  perception  can 
be  illustrated  only  by  the  selection  of  objects  in  which 
certain  of  the  common  laws  may  be  exemplified.  Speak- 
ing generally,  it  may  be  said  that  perception  is  practically 
never  merely  a  mass  of  bare  sensations.  The  sensations 
at  most  provide  a  suggestion  which  is  developed  in  con- 
sciousness to  make  the  object  as  we  appreciate  it.  In 
optical  illusions,  certain  elements  are  added,  certain 
others  are  subtracted  from  the  immediate  group  of 
sensations,  before  we  have  the  final  percept.  One  is 
not  aware  of  either  the  additions  or  the  subtractions, 
much  less  of  the  sensations  as  immediately  given  before 
the  modifications  are  made.  This  same  process  may 
be  demonstrated  to  take  place  in  practically  every 
perception  before  we  attain  what  we  call  the  real  object. 
We  are  aware  only  of  the  final  process,  the  object,  but 
we  can  be  sure  from  experimental  data  that  this  is  not 
the  immediate  result  of  sensation,  but  is  the  result  of  a 
complicated  series  of  mental  operations. 

Reading.  —  One  of  the  best  means  of  studying  the 
various  laws  of  perception  as  they  apply  to  ordinary 
material  is  furnished  by  reading.  Here  the  material  is 
relatively  simple  and  we  have  fairly  full  experimental 
evidence  concerning  the  different  phases  of  the  process. 
First  it  may  be  asserted  that  the  word,  not  the  letter, 
is  the  unit  for  reading.  This  is  demonstrated  by  the 
experiment  on  the  distribution  of  attention.  As  was 
said  in  connection  with  attention,  five  or  six  letters  is 
the  maximum  that  can  be  distinguished  on  short  expos- 
ure, but,  when  combined  into  words,  twenty-five  to 
thirty  letters  may  be  read  at  a  single  exposure  of  Th 


READING  337 

second.  E\adently  something  must  be  added  to  what 
is  seen,  or  the  word  must  be  read  as  a  whole  rather  than 
by  single  letters.  There  is  e\idence  that  both  processes 
go  on  in  some  degree.  Zeitler  and  the  writer  found  that 
the  reader  was  influenced  by  the  general  form  of  the 
word  as  determined  by  the  relative  positions  of  high 
and  low  letters,  the  length  of  the  letters,  etc.  This  is 
indicated  again  in  print  by  the  fact  that  one  is  much 
more  likely  to  make  mistakes  and  to  have  greater  diffi- 
culty in  making  out  the  words  if  the  upper  parts  of  the 
words  are  cut  off  than  if  the  lower  be  covered. 

On  the  other  hand,  the  proofreader's  illusion  indi- 
cates that  there  is  a  constant  tendency  to  supply  letters 
or  parts  of  letters  from  memory,  to  add  centrally  to 
peripherally  aroused  sensations.  The  writer  found  that 
if  words  were  printed  with  letters  omitted,  with  blurred 
letters,  or  with  substitutions,  and  shown  for  a  fifth  of 
a  second  or  less,  they  were  read  in  a  large  proportion  of 
the  cases  as  if  perfect.  The  readers  would  occasionally 
give  reports  of  the  character  of  the  letters,  supplied 
or  transformed,  which  indicated  that  they  belonged  in 
the  class  of  the  centrally  aroused  sensations.  The  let- 
ters that  were  supplied  or  replaced  were  faint  or  in  a 
peculiar  color,  or  seemed  to  be  less  permanent  than 
the  others.  The  likelihood  of  reading  the  misprinted 
word  as  if  it  were  correctly  printed  was  much  increased 
by  calling  a  word  associated  with  the  word  to  be  shown 
before  the  exposure.  This  gave  the  right  attitude  or 
setting  for  seeing  the  word  intended.  That  supplement- 
ing plays  a  part  in  the  simplest  reading  is  shown  by  the 
large  number  of  misprints  that  are  overlooked,  some 


338  FUNDAMENTALS   OF   PSYCHOLOG^y 

even  by  the  most  accurate  proofreaders.  We  may  as- 
sume as  a  beginning  that  reading  is,  in  part,  a  process  . 
of  seeing  and,  in  part,  a  process  of  supplying  from  mem- 
ory what  we  believe  to  be  present.  The  supplements 
in  this  case  are  not  so  permanent  as  are  those  in  optical 
illusions.  The  latter  persist  for  a  considerable  time  in 
spite  of  all  that  one  can  do,  and  can  be  destroyed  only 
by  a  long  period  of  practice,  but  the  proofreader's 
illusion  vanishes  when  first  one  looks  to  make  sure  that 
a  mistake  has  not  been  made. 

Reading  Pauses.  —  One  might  deny  that  the  condi- 
tions of  ordinary  reading,  in  which  all  the  time  that  may 
be  desired  is  given  for  looking,  are  similar  to  those 
in  which  the  exposure  is  limited  to  a  period  too  short 
to  permit  eye  movements  or  wandering  of  attention. 
Recent  studies  of  the  mechanism  of  reading  show,  how- 
ever, that  the  conditions  are  not  markedly  different.  In 
the  first  place  it  has  been  found  that,  while  reading, 
the  eyes  do  not  move  steadily  along  the  line  with  full 
time  for  the  observation  of  all  details,  but  make  a  few 
brief  pauses.  Photographs  of  the  eyes  as  they  move 
along  the  line  show  that  they  stop  only  from  three  to  six 
times  in  a  line  of  ordinary  length,  and  then  for  but  a 
very  short  time,  approximately  a  fifth. of  a  second.  The 
number  of  stops  varies  greatly  with  the  character  of 
the  material  to  be  read.  In  reading  a  novel  or  similar 
light  literature,  the  number  is  a  minimum  and  rises  to 
a  maximum  with  difficult  material,  in  proofreading,  and 
for  children  who  are  learning  to  read.  One  really  takes 
a  series  of  snap  shots  of  a  line  and  pieces  it  together 
from  those,  rather  than  reading  continuously.     There  is 


READING  339 

apparently  no  reading  while  the  eyes  are  in  motion; 
they  move  so  rapidly  that  nothing  but  a  blur  of  after 
images  is  left  on  the  retina,  and  as  this  gives  no  knowl- 
edge, we  have  learned  to  pay  no  attention  to  it. 

Reading  a  Process  of  Supplementation.  —  All  this 
leads  to  the  conclusion  that  ordinary  reading  is  a  process 
of  inferring  unconsciously  from  the  form  of  the  words 
and  a  few  letters  what  the  word  actually  is.  This 
process  of  inference  is  really  nothing  more  than  asso- 
ciating with  the  letters  seen  certain  other  letters  fre- 
quently found  with  them,  or  of  associating  whole  words 
with  what  little  of  the  w^ord  is  seen.  Like  all  associa- 
tions, these  are  under  the  control  of  the  mental  attitude, 
largely  determined  by  the  context  and  the  knowledge 
that  the  reader  can  bring  to  the  reading.  The  influence 
of  the  context  can  be  seen  in  the  different  pronuncia- 
tion and  interpretation  of  a  word  composed  of  the  same 
letters  in  different  contexts.  '  Lead  '  has  one  pronun- 
ciation when  the  subject  of  the  sentence,  another  when 
it  is  the  predicate,  and  one  does  not  think  of  the  one 
when  the  other  is  meant.  The  difference  is  altogether 
in  the  context,  and  what  has  gone  before.  Still  more 
striking  is  the  difference  in  pronunciation  and  inter- 
pretation that  attaches  to  the  same  letters  in  different 
languages.  Man  has  an  entirely  different  sound  and 
meaning  in  English  and  in  German,  and  many  other 
illustrations  could  be  found.  Suffice  it  to  say  that 
the  sounds  or  ideas  that  are  aroused  depend  very  defi- 
nitely upon  the  context. 

In  reading  it  is  evident,  too,  that  the  process  of  per- 
ceiving or  of  interpreting  is  not  complete  when  the 


340  FUNDAMENTALS   OF  PSYCHOLOGY 

word  as  such  has  been  seen.  The  process  of  translation 
into  ideas  follows.  Sometimes  one  sees  the  words  and 
follows  them  along  with  the  sound  of  the  spoken  word, 
and  then  has  the  ideas  associated  with  them.  More 
frequent  in  the  adult  is  the  immediate  translation  of 
the  words  as  seen  into  images  or  ideas  of  some  sort.  As 
one  reads  in  the  most  complete  way,  pictures  or  more 
abstract  ideas  accompany  the  reading.  The  clearer 
the  style,  the  more  immediately  do  the  ideas  follow 
upon  the  perception  of  the  words  and  the  less  prominent 
are  the  words,  until  with  a  maximum  of  clearness  the 
words  are  largely  neglected  and  the  meaning  alone  comes 
to  consciousness.  This  meaning  may  take  the  form  of 
picturing  the  scenes  described,  of  merely  appreciating 
the  abstract  meaning,  or  of  something  intermediate.  In 
any  case,  the  outlines  of  black  and  white  that  constitute 
the  words  start  the  association  processes  that  lead  to 
the  ideas,  and  these  associates  are  controlled  by  the 
wider  setting  and  wider  knowledge  of  the  individual  at 
the  moment.  The  process  is  much  like  that  in  ordinary 
recall  except  that  the  stimuli  are  constantly  received 
from  the  words.  The  revival  of  the  earlier  experiences 
is  controlled  by  the  laws  of  association  and  by  the  con- 
text in  a  degree  that  practically  amounts  in  many  cases 
to  new  construction. 

Understanding  Spoken  Language.  —  A  similar  pro- 
cess occurs  in  listening  to  another's  speech.  One  does 
not  appreciate  how  small  is  the  proportion  of  a  conversa- 
tion that  is  heard  distinctly  until  one  attempts  to  follow 
a  foreign  language.  Then  it  is  seen  that  what  must  be 
perfectly  clear  to  a  native  as  a  vehicle  for  ideas  is  really 


READING  341 

only  a  series  of  grunts  and  hisses  with  an  occasional 
word  clearly  enunciated.  Suggested  by  these,  the  words 
or  the  ideas  are  supplied  through  association.  Bagley 
has  shown  that  there  is  a  process  of  filling  out  the  im- 
perfections of  sounds  similar  to  that  we  have  seen  to 
occur  in  reading.  The  laws  of  supplementing  are  prac- 
tically the  same  in  the  two  cases.  Something  is  given 
by  the  ear,  this  suggests  words  as  one  would  speak  them 
one's  self  or  as  they  would  look  on  the  printed  page. 
This  is  all  that  is  really  appreciated,  and  even  when  one 
listens  for  the  words,  the  imperfections  are  not  noticed. 
When  one  hears  a  strange  accent,  the  different  devia- 
tions from  the  sounds  one  is  accustomed  to  are  over- 
looked, the  man  is  assigned  to  his  region  of  the  country, 
and  then  no  more  attention  is  paid  to  the  speech  char- 
acteristics, unless  one  be  interested  in  phonetics  or  have 
some  other  purpose  in  hearing  the  sounds,  and  then  the 
sense  of  what  is  being  said  is  very  likely  to  be  lost. 
Artificial  languages  gradually  take  on  the  same  char- 
acter. The  separate  elements  become  united  into  word 
units,  and  then  take  on  meaning  as  do  words  themselves. 
This  comes  out  particularly  clearly  in  learning  the  tele- 
graphic language.  There  at  first  the  sounds  are  heard 
as  small  groups  and  put  together  painstakingly  and 
slowly  into  letters,  but  gradually  words  are  heard  as 
wholes  and'  the  meaning  is  suggested  by  a  few  words 
and  omissions  filled  in  as  in  ordinary  speech.  Supple- 
menting follows  the  same  laws  as  in  reading  or  listening. 
If  one  may  extend  and  generalize  the  laws  of  percep- 
tion in  reading  and  listening,  it  may  be  said  that  per- 
ception is  primarily  a  process  of  arousing  old  experiences 


342  FUNDAMENTALS    OF   PSYCHOLOGY 

through  association.  These  associations  are  controlled 
by  both  the  subjective  and  the  objective  factors.  Some 
few  sensations  always  serve  as  the  incentive  to  the  per- 
ception process,  but  they  serve  as  the  incentive  only. 
By  them  associations  are  aroused  and,  in  the  arousal 
of  the  associations,  all  the  experiences  that  have  had 
any  bearing  on  the  process  play  a  part.  Some  of  the 
associations  are  determined  through  mere  frequency 
of  appearance  with  the  original  stimulus ;  more  depends 
upon  the  attitude  in  which  one  is  at  the  moment  of 
looking  or  listening,  and  upon  the  inherent  probabilities 
of  the  situation.  That  one  is  not  more  often  misled 
is  due  to  the  fact  that  objective  situations  repeat  them- 
selves so  frequently,  quite  as  frequently  as  do  ideas. 
It  is  safe  on  the  whole  to  assume  that  what  we  take  as 
the  sign  of  an  old  situation  really  accompanies  that 
situation,  for  in  the  vast  majority  of  cases  the  remainder 
of  the  elements  are  actually  present.  In  practice  it 
would  take  more  trouble  to  stop  to  investigate  than 
to  take  the  chance  and  be  wrong  the  few  times  that  the 
new  does  not  correspond  to  the  old.  It  is  striking,  how- 
ever, that  in  this  case  alone  one  does  not  distinguish 
between  real  sensations  and  the  recalled  images.  Cen- 
trally and  peripherally  aroused  sensations  are  combined 
in  almost  all  perceptions,  but  one  never  can  tell  where 
the  sensations  stop^  and  mental  supplements  begin. 
One  seems  as  real  as  the  other. 

The  Influence  of  the  Type  in  Perception.  —  One 
other  general  law  of  perception  may  be  an  outcome  of 
those  already  mentioned  but  probably  contains  in  addi- 
tion elements  that  connect  perception  with  the  reason- 


THE    CONCEPT    IN    PERCEPTION  343 

ing  processes,  —  this  is  the  tendency  to  replace  a  par- 
ticular phase  or  aspect  of  an  object  by  what  has  proved 
to  be  its  more  general  or  universal  form.  Usually  one 
sees  things  as  the  previous  experience  convinces  one 
they  must  be,  rather  than  as  they  appear  at  the  par- 
ticular moment.  Thus,  one  usually  does  not  notice 
shadows  as  shadows,  although  they  may  play  a  consider- 
able part  in  the  interpretation  of  the  form  of  the  surface 
on  which  they  fall.  Similarly,  one  does  not  notice  how 
indistinct  are  objects  in  the  field  of  vision  a  little  dis- 
tance from  the  fixation  point.  What  is  seen  is  at  once 
translated  into  an  object  of  perfect  form  with  full  detail 
and  distinctness,  and  all  else  serves  as  a  mere  background. 
Still  more  striking  is  the  correction  of  the  size  of  various 
objects  mentioned  above.  The  standard  size  varies  for 
the  different  objects.  No  matter  how  small  or  how  large 
the  image  may  be  under  a  given  set  of  circumstances, 
it  is  increased  or  decreased  to  a  standard  size.  The 
image  itself  is  never  seen,  the  fact  that  it  has  been 
changed  in  its  size  also  is  not  noticed;  the  corrected 
standardized  impression  at  once  replaces  the  original 
image.     This  standard  we  regard  as  the  real  object. 

Similar  tendencies  to  replace  mere  sensation  groups 
by  concepts  or  by  standardized  objects  may  be  seen  any- 
where. The  neglect  of  after-images,  of  contrast  colors, 
the  overlooking  of  imperfections  in  the  media  of  the 
eye  that  can  be  seen  clearly  when  one  looks  for  them  in 
a  lamp  flame,  overlooking  the  retinal  blood  vessels  in 
the  \dsual  field,  —  all  of  these  omissions  are  quite  as 
apparent  as  is  the  addition  of  qualities  or  character- 
istics not  given  in  sensation.     Equally  striking  are  the 


344  FUXDAMZXTALS    OF   PSYCHOLOGY 

changes  in  the  forms  of  objects  seen  in  perspective.  As 
any  article  of  furniture  is  looked  at,  the  square  comers 
are  either  increased  to  oblique  angles  or  reduced  to  acute 
angles,  according  to  the  side  from  which  one  looks.  A 
hundred  students  looking  from  different  directions  at 
the  lecturer's  reading  desk  will  each  receive  a  different 
impression,  different  in  shape  as  well  as  in  size,  but  the 
object  is  the  same  for  all.  The  perception  is  changed 
in  being  seen,  or  a  standard  object  is  made  to  replace 
the  various  images,  so  that  the  final  result  is  the  same  for 
each  observer.  This  process  of  replacing  the  crude 
image  by  a  standard  object,  an  object  that  has  been 
developed  by  all  of  the  iiidi\*iduars  experiences,  that 
has  been  gradually  corrected  by  being  seen  under  differ- 
ent conditions,  by  being  handled,  and  even  by  making 
similar  objects  or  seeing  them  made,  is  practically 
universal.  It  is  the  developed  standard  object  that 
always  comes  to  consciousness,  just  as  it  is  the  corrected 
standard  space  that  is  always  used  as  the  basis  of  refer- 
ence. To  anticipate  the  discussion  of  a  later  problem 
it  may  be  said  that  we  perceive  concepts  rather  than 
sensations.  As  concepts  that  have  developed  in  this 
way,  we  have  not  merely  objects,  but  space  and  time 
and  similar  abstractions  which  are  in  part  components 
of  the  objects,  in  part  to  be  regarded  as  independent. 


CPL\PTER   X 

MEMORY 

Memory  is  a  topic  that  bulks  very  large  in  the  discus- 
sion of  daily  life.  It  may  be  defined  as  the  awareness  of 
the  fact  that  a  certain  event  has  been  experienced  in  the 
past.  In  the  complete  form  it  may  be  defined  as  the  recur- 
rence of  a  group  of  experiences  vdth  knowledge  of  when 
and  where  they  were  experienced  before.  ]\Iemory  is 
related  to  centrally  excited  sensation  in  very  much  the 
same  way  that  perception  is  related  to  sensations.  It  is 
a  group  of  centrally  excited  sensations  accepted  as  repre- 
sentLQg  some  earlier  seen  object  or  preWous  event,  as 
perception  represents  an  object  actually  present.  Unlike 
sensations,  whether  of  peripheral  or  central  origin,  both 
are  concrete  mental  processes,  not  mere  abstractions. 
All  of  the  actual  materials  of  memor}'  and  the  laws  that 
are  involved  in  the  recurrence  of  ideas  have  been  discussed 
in  connection  with  centrally  aroused  sensations,  save  only 
in  so  far  as  these  involve  meaning  and  recognition,  — 
the  fact  that  the  processes  recalled  represent  things  and 
are  referred  to  the  correct  period  in  the  past. 

\Miile  the  fundamentals  of  memory  have  been  dis- 
cussed, there  is  much  of  more  particular  application  that 
remains  to  be  considered  —  questions  as  to  how  the  asso- 
ciation processes  may  be  used  to  the  best  advantage  in 
the  accumulation  and  appb'cation  of  knowledge.     We 

345 


346  FUNDAMENTALS   OF  PSYCHOLOGY 

may  conveniently  divide  memory  into  four  part  processes, 
— learning,  retention,  recall,  and  recognition.  Learning  is 
no  more  than  the  formation  of  association,  and  retention 
their  persistence ;  but  while  both  have  been  treated  in 
general,  we  must  consider  here  a  large  number  of  special 
rules  and  laws  developed  through  experiment  that  throw 
new  light  on  the  nature  and  use  of  memory.  If  learning 
has  to  do  with  the  formation  of  connections,  recall  de- 
pends upon  the  degree  in  which  the  associations  may 
become  effective.  To  have  the  associations  is  not  iden- 
tical with  being  able  to  use  them.  We  may  weave  to- 
gether the  results  obtained  from  experiments  on  the  first 
three  processes,  before  we  consider  recognition  which 
involves  certain  relatively  new  principles. 

Experimental  Methods.  —  Careful  experiments  on 
memory  were  first  made  by  Ebbinghaus  in  the  eighties 
of  the  last  century.  To  avoid  the  variation  in  degree  of 
famiharity  and  interest  that  might  attach  to  words  or 
any  other  material  that  has  meaning,  nonsense  syllables 
were  selected  as  the  material  to  be  learned.  These  were 
built  up  systematically  of  all  possible  combinations  of 
consonants  and  vowels,  two  consonants  with  a  vowel 
between.  All  were  excluded  that  chanced  to  make  sense. 
Series  were  selected  by  lot  from  the  mass  of  syllables. 
Ebbinghaus  wrote  his  series  upon  cards  and  then  learned 
them  by  shuffling  the  cards.  Most  later  workers  have 
arranged  the  syllables  upon  some  sort  of  revolving  drum 
that  exposes  them  at  regular  intervals  and  for  definite 
times.  They  are  said  through  regularly  as  they  are 
exposed,  until  they  can  be  repeated  once  or  twice  without 
mistake.     Ebbinghaus  measured  the  amount  of  effort 


MEMORY  347 

in  learning  by  the  time  required,  but  most  later  writers 
have  chosen  the  number  of  repetitions  as  the  measure. 
Two  methods  have  been  used  to  test  the  accuracy  of  the 
learning  or  the  amount  of  retention.  The  first,  known 
as  the  method  of  relearning,  was  used  by  Ebbinghaus. 
It  consisted  in  relearning  the  syllables,  and  assumed  that 
the  difference  between  the  time  required  for  learning  and 
for  relearning  was  a  measure  of  the  amount  retained. 
This  also  measured  the  value  of  the  method  of  learning 
used.  In  a  second  method,  developed  by  Miiller  and 
Schumann  and  extensively  used  since,  the  syllables  are 
learned  in  pairs  and  the  amount  retained  is  measured  by 
showing  the  first  of  each  pair  and  determining  the  number 
of  times  the  second  syllable  may  be  supphed.  The  per- 
centage of  correct  answers  indicates  the  amount  retained. 
In  many  experiments,  the  time  required  for  speaking  the 
second  syllable  is  measured.  This  serves  as  an  indication 
of  the  strength  of  the  association  for  individual  pairs. 
The  shorter  the  interval  required,  the  stronger  is  the 
association.  Each  of  these  methods  has  given  valuable 
results.  They  frequently  supplement  each  other.  The 
first  measures  primarily  the  learning  of  the  series  as 
wholes,  while  the  second  permits  a  study  of  the  learning 
of  individual  pairs  and  of  parts  of  the  series  as  well. 

The  Laws  of  Learning 

Effect  of  Individual  Repetitions.  —  One  of  the  first  pre- 
liminaries to  the  application  of  the  method  was  to  deter- 
mine the  accuracy  of  the  method  itself.  One  of  the  most 
important  of  these  was  to  discover  the  effects  produced 


348  FUNDAMENTALS   OF  PSYCHOLOGY 

by  each  repetition  when  a  number  of  repetitions  are  made 
of  the  same  series.  One  might  expect  that  later  repeti- 
tions would  be  less  effective  than  the  earher.  Ebbing- 
haus  tested  this  by  repeating  a  series  of  syllables  eight 
times  and  then  finding  the  time  required  to  relearn  after 
twenty-four  hours.  He  then  repeated  another  series 
sixteen  times  and  again  relearned  after  the  same  interval. 
These  experiments  were  repeated  up  to  sixty-four  repe- 
titions of  a  series.  He  found  that  the  saving  after 
twenty-four  hours  was  directly  proportional  to  the  num- 
ber of  original  repetitions.  The  last  repetitions  were  no 
less  effective  than  the  first  as  measured  by  the  amount 
retained.  The  diagram  shows  that  the  results,  when 
plotted,  lie  almost  in  a  straight  hne.  Each  repetition 
resulted  in  a  saving  of  about  twelve  seconds  in  the 
time  required  for  relearning.  This  experiment  brings 
out  the  fact  that  learning  is  never  absolutely  complete 
or  perfect.  Perfect  learning  at  the  moment  will  show 
defects  in  a  few  hours  or  days,  and  the  time  and 
accuracy  of  retention  may  be  increased  by  repetitions 
much  beyond  the  number  required  for  the  first  perfect 
repetition.  Each  repetition  will  have  the  same  effect 
as  any  other  in  the  recall  of  the  next  day  or  of  the 
next  week. 

Relation  between  Length  of  Series  and  Number  of 
Repetitions.  —  One  of  the  more  striking  facts  in  connec- 
tion with  learning  is  the  great  increase  in  the  number  of 
repetitions  required  for  the  longer  series  as  compared 
with  the  shorter.  It  is  found  that  an  adult  can  remember 
from  six  to  eight  syllables  or  eleven  to  thirteen  numbers 
with  a  single  repetition,  while  Ebbinghaus  found  that  it 


MEMORY  349 

took  13  repetitions  to  learn  a  series  of  10  syllables,  16.6 
for  12,  30  for  16,  44  for  24,  55  for  36.  As  the  number 
of  syllables  in  a  series  increases,  the  number  of  repetitions 
required  for  learning  it  increases  much  more  rapidly  than 
in  proportion  to  the  increase  in  the  number  of  syllables. 
The  most  striking  increase  is  seen  when  the  series  is  just 
longer  than  can  be  learned  with  one   repetition.     The 


0  8  ^6  24  32  42  53  64 

Fig.  87.  —  Shows  the  increase  in  amount  retained  after  twenty -four  hours 
with  the  number  of  repetitions.  The  number  of  repetitions  is  plotted  on  the 
horizontal,  the  saving  in  seconds  on  the  vertical  axis. 

number  of  syllables  that  may  be  taken  in  at  a  single 
reading  has  been  called  the  memory  span,  or  primary 
memory.  This  varies  very  markedly  with  age,  with 
training,  and  with  the  individual.  It  may  be  much  in- 
creased by  training  at  any  age.  According  to  Meumann, 
children  from  seven  to  nine  can  usually  retain  no  more 
than  two  or  three  nonsense  syllables,  while  the  practised 
adult  retains  seven  or  eight. 


3  so  FUNDAMENTALS   OF  PSYCHOLOGY 

Effects  of  Grouping.  —  Learning  a  series  not  only 
makes  associations  between  the  contiguous  syllables  of 
the  sei'ies,  but  knits  the  whole  group  together  by  associ- 
tions  formed  between  all  of  the  syllables,  however  widely 
they  may  be  separated.  Ebbinghaus  demonstrated 
this  by  first  learning  series  and  then  making  up  new  series 
that  should  consist  in  part  of  the  syllables  of  the  primary 
ones.  Thus,  he  would  select  syllables  that  had  been  sep- 
arated by  one  syllable,  and  found  that  the  new  series 
could  be  learned  more  easily  than  new  syllables.  He 
repeated  the  experiment,  using  syllables  that  had  been 
separated  by  two,  three,  etc.,  syllables  up  to  those  that 
had  been  separated  in  the  original  learning  by  as  many  as 
eight.  He  found  in  each  case  that  a  saving  could  be 
shown  as  compared  with  entirely  new  series.  The  results 
prove  that,  in  a  series,  associations  are  formed  between 
the  remote  as  well  as  the  contiguous  elements.  He  also 
showed  that  associations  are  formed  in  both  directions, 
backward  as  well  as  forward.  Relearning  a  series  back- 
ward saves  about  one-third  of  the  time  saved  in  relearn- 
ing forward.  It  has  also  been  shown  that  there  is  some 
connection  formed  between  the  syllable  and  its  position  in 
the  series.  Syllables  that  are  relearned  in  the  same  abso- 
lute position  in  a  series  are  relearned  more  easily  than 
when  they  take  a  new  position.  If  the  syllable  is  the 
third  or  the  seventh  in  the  series  and  is  kept  in  third  or 
seventh  place,  relearning  is  easier  than  if  it  is  shifted  to 
second  or  fifth  place  in  the  new  series.  All  of  these  bonds 
of  connection  serve  to  make  the  series  a  unit. 

Effects  of  Rhythm.  —  Anything  that  serves  to  unite  the 
syllables  into  minor  units  is  of  advantage  in  aiding  learn- 


MEMORY  351 

ing.  One  of  the  means  employed  most  frequently  is 
rhythm.  In  repeating  a  series,  the  syllables  are  prac- 
tically always  combined  in  rhythmic  units  and  given  an 
accent.  Learning  in  the  natural  rhythm  is  much  easier 
than  in  a  forced  rhythm  or  without  rhythm.  The  natural 
rhythm  varies  with  the  indi\idual  and  probably  also 
with  the  race,  but  whatever  the  rhythm  used,  some  bene- 
fit is  derived  from  it.  The  rhythmic  unit  also  serves  as  a 
subordinate  group  within  which  associations  are  much 
stronger  than  betw^een  contiguous  syllables  of  different 
groups.  ]\Iuller  demonstrated  this  by  first  learning  series 
in  trochaic  rhythm  and  then  forming  from  the  syllables 
two  sets  of  new  syllables.  In  one  of  these,  the  syllables 
were  relearned  in  the  same  measures  as  in  the  original 
series ;  in  the  others,  the  syllables  were  contiguous  but 
had  belonged  to  different  measures.  The  former  showed 
a  sa\ing  on  relearning  equivalent  to  five  repetitions  ;  the 
latter,  no  appreciable  sa\ing.  This  strong  association 
within  the  group  holds,  not  merely  for  the  grouping  in 
rhythmic  units,  but  for  any  grouping.  In  learning  non- 
sense syllables,  there  is  practically  no  association  formed 
between  the  first  syllable  of  one  series  and  the  last  of  the 
preceding.  In  common  fife  Httle  connection  is  estab- 
Hshed  between  conversations  on  different  subjects  with 
different  persons,  even  if  one  immediately  succeeds 
the  other.  On  the  other  hand,  where  material  to  be 
remembered  is  broken  up  into  smaller  groups  of  a  larger 
series,  members  of  these  groups  are  more  closely  asso- 
ciated for  themselves,  and  learning  the  groups  aids  in 
learning  the  total  series.  This  formation  of  subordinate 
groups  is  of  great  practical  importance,  and  we  shall  have 


352  FUNDAMENTALS   OF    PSYCHOLOGY 

occasion  to  refer  to  it  in  connection  with  the  development 
of  meaning. 

Learning  by  Whole  and  Part.  —  Of  the  more  practical 
laws  for  learning,  one  of  the  most  important  is  that  it  is 
much  easier  to  learn  any  selection  if  it  is  repeated  as  a 
whole  instead  of  by  parts.  This  appHes  to  nonsense 
material  under  strict  experimental  conditions,  but  is  of 
more  interest  in  connection  with  learning  selections  that 
have  meaning,  poems,  etc.  The  investigations  were  first 
carried  out  by  Miss  Steffens  under  the  direction  of  Pro- 
fessor Miiller.  They  consisted  in  comparing  the  time 
required  for  poems  when  learned  as  most  people  incHne  to 
learn  them,  a  hne  or  a  couplet  at  a  time,  with  the  time 
required  when  they  are  read  through  from  beginning  to 
end  each  time.  The  results  indicate  that  in  practically 
every  case  learning  as  a  whole  is  more  economical  than 
learning  in  parts.  The  saving  amounted  to  about  ten 
per  cent  in  Miss  Steffens'  experiments  and  held  for 
children  as  well  as  for  adults.  Later  investigations  by 
Meumann  showed  that  two  stanzas  required  thirty-three 
repetitions  by  the  part  method,  and  only  fourteen  for 
the  whole  procedure.  It  should  be  said  that  unless  some 
method  of  keeping  the  repetitions  at  a  uniform  rate  be 
employed,  the  learner  tends  to  lose  interest  and  to  repeat 
more  slowly  than  he  will  if  he  is  permitted  to  learn  by 
parts.  In  some  experiments  it  has  been  shown  that  this 
loss  in  rate  almost  compensated  for  the  gain  in  repetitions. 
With  practice,  this  may  be  overcome.  That  the  principle 
is  correct  has  been  shown  repeatedly,  since  not  only 
does  learning  require  fewer  repetitions,  but  the  material 
learned  as  a  whole  is  much  better  retained  than  material 


MEMORY  353 

learned  in  parts.  There  is  also  a  fairly  wide  limit  of 
application,  as  the  whole  method  was  found  more 
economical  by  Pyle  for  selections  that  required  as  much 
as  fifty  minutes  to  read  through. 

The  reasons  for  the  greater  efiiciency  are  threefold. 
I .  They  save  much  of  the  time  ordinarily  wasted  in  need- 
less repetitions.  In  the  part  method,  the  first  part  of  the 
selection  is  repeated  more  times  than  necessary  through 
going  back  to  connect  the  later  learned  with  the  earlier. 
There  are  several  times  as  many  repetitions  of  the  first 
as  of  the  later.  2.  Needless  associations  are  made  each 
time  the  reader  goes  back  from  the  end  of  a  Hne  to  its 
beginning.  These  take  time  and  also  may  interfere  with 
the  formation  of  the  correct  associates.  3.  As  was  said 
above,  the  connection  of  a  word  with  its  position  in  the 
selection  is  of  some  advantage  in  learning,  and  the  whole 
method  always  retains  the  absolute  position  of  each 
word.  Meumann  and  his  pupils  have  shown  that  certain 
intermediate  methods  may  improve  on  the  strict  method. 
Thus,  it  is  frequently  an  advantage,  after  a  number  of 
repetitions  of  the  whole,  to  repeat  several  times  the  parts 
of  the  selection  that  offer  special  difficulties,  and  to  learn 
them  without  making  unnecessary  repetitions  of  the 
easier  portions.  One  can  also  obtain  some  of  the  advan- 
tages of  the  part  method  by  making  pauses  at  certain 
places,  and  then  going  on  from  that  place  after  a  few 
seconds.  These  pauses  seem  to  attract  particular  atten- 
tion to  the  words  preceding  and  succeeding  them,  with- 
out the  disadvantage  of  forming  useless  connections. 
In  general,  it  is  recommended  that  one  read  through  the 
selection  to  be  learned  a  few  times  as  a  whole,  then,  as 


354  FUNDAMENTALS   OF   PSYCHOLOGY 

fatigue  comes  on,  introduce  the  pauses,  and,  when  it 
becomes  evident  that  certain  parts  are  offering  special 
difficulties,  make  an  extra  number  of  repetitions  of  those 
parts  until  they  are  learned,  then  add  a  few  repetitions  of 
the  whole  to  weld  all  together. 

Distributed  Repetitions  More  Effective.  —  Another 
law  that  is  equally  well  established,  quite  as  important 
in  practice,  and  even  more  interesting,  is  the  so-called  law 
of  divided  repetitions.  Briefly,  this  is  that  the  more  the 
repetitions  are  distributed  over  different  days,  the  fewer 
the  repetitions  required  and  the  more  thoroughly  the 
material  is  mastered.  It  was  first  carefully  investigated 
by  Jost.  He  tried  learning  nonsense  syllables  with 
twenty-four  repetitions  at  one  time,  then  similar  series 
with  eight  repetitions  per  day  for  three  days,  then  four  for 
six  days,  and  finally  two  a  day  for  twelve  days.  It  was 
found  when  they  were  tested  by  the  method  of  paired 
associates  twenty-four  hours  after  the  last  repetition, 
that  the  fewer  the  repetitions  each  day,  the  greater  was 
the  amount  retained.  Ebbinghaus  had  earher  compared 
greater  numbers  of  repetitions.  On  one  occasion  he 
read  a  series  of  twelve  syllables  68  times  and  found 
that  twenty-four  hours  later  he  needed  seven  repetitions 
to  relearn.  Then  he  repeated  another  of  the  same  length, 
17I,  12,  and  Sj  times,  a  total  of  :^S,  and  found  but  five 
repetitions  were  needed  for  relearning  twenty-four  hours 
later.  Still  later  Miss  Perkins  continued  the  extension 
of  distributions,  comparing  accumulated  repetitions  of 
eight  a  day  for  two  days,  with  four  and  two  and  one  repe- 
tition per  day,  every  other  day,  every  third,  and  every 
fourth  day.     The  results  were  tested  after  fourteen  days 


MEMORY  ,  355 

and  proved  even  more  striking  than  those  of  the  earlier 
tests  which  were  made  after  twenty- four  hours.  Eight 
repetitions  a  day  gave  only  from  9  to  17  per  cent  correct 
responses,  and  the  larger  number  was  obtained  when  three 
days  were  permitted  to  elapse  between  each  series  of 
eight  repetitions.  Four  readings  a  day  gave  from  25  to 
41  per  cent,  with  larger  values  for  the  wider  distribu- 
tion of  repetitions ;  two  a  day  gave  from  45  to  78  per 
cent,  while  a  single  repetition  every  day  gave  79  per 
cent;  a  single  repetition  every  other  day,  72  per  cent; 
every  third  day,  82  per  cent,  and  every  fourth  day,  68 
per  cent.  It  would  seem,  then,  that  one  repetition 
every  second  or  third  day  gives  a  maximum  value 
for  learning. 

This  law  has  been  tested  a  number  of  times  on  children 
and  adults,  and  even  on  the  learning  of  animals,  and  al- 
ways vdih  the  same  results.  Ulrich  ^  found  that  white  rats 
could  learn  a  maze  with  fewest  repetitions  if  they  were 
given  one  trial  each  third  day.  It  holds  also  for  sense 
material  as  well  as  for  nonsense  syllables.  The  explana- 
tion of  the  advantage  of  divided  repetitions  was  suggested 
by  some  of  the  experiments  of  Jost.  He  found  that, 
when  he  compared  the  number  of  repetitions  required 
to  completely  develop  two  sets  of  associates  of  equal 
strength  but  of  different  ages,  the  older  required  fewer 
repetitions  than  the  younger.  His  method  was  to  learn 
one  series  of  syllables  twenty-four  hours  before  and  then 
to  make  a  few  repetitions  of  another  series  a  few  hours 
before  the  test.  The  amount  retained  was  tested  by  the 
method  of  paired  associates.     When  three  times  as  many 

1  Watson,  Animal  Beha\-ior,  pp.  228  ff. 


356  FUNDAMENTALS   OF  PSYCHOLOGY 

correct  associates  could  be  given  from  the  newer  series, 
it  required  almost  the  same  number  of  repetitions  to 
bring  each  to  the  point  where  it  could  be  said  through 
without  mistake.  When  the  number  of  correct  asso- 
ciates that  could  be  given  was  approximately  the  same 
for  both  series,  the  older  series  could  be  fully  learned  much 
more  easily  than  the  more  recent.  His  theory  is  that  the 
associations  continue  to  grow  strong,  to  '  set,'  for  some 
time,  perhaps  for  two  or  three  days  after  they  are  first 
formed.  That  associations  tend  to  increase  in  strength 
for  a  few  days  is  known  as  '  Jost's  Law.'  This  unearned 
increment  that  comes  from  the  setting  process  makes  it 
much  easier  to  bring  them  back  to  full  effectiveness  some 
time  after  the  learning,  than  if  no  time  is  permitted 
to  elapse  after  the  repetitions  are  first  made.  It  is 
possible  to  connect  this  setting  process  with  the  con- 
tinued activity,  perseveration  tendency,  that  makes 
possible  the  primary  memory  or  immediate  retention, 
and  is  one  more  expression  of  the  inertia  of  the  nervous 
system. 

Several  important  practical  deductions  may  readily 
be  drawn  from  this  law.  Obviously,  it  is  a  close  corollary 
of  the  preceding  law,  since,  if  one  is  to  read  through  each 
time,  only  short  selections  could  be  learned  in  any  one 
day.  Coupled  with  the  advantage  from  divided  repeti- 
tions, it  gains  full  force,  since,  if  the  selection  be  not 
learned  at  the  first  sitting,  it  is  an  advantage  to  wait  a 
day  or  two  before  proceeding  to  complete  the  learning. 
Again  the  bearing  upon  the  familiar  topic  of  cramming 
is  quite  evident.  What  is  repeated  often  at  periods  con- 
siderable distances  apart  is  learned   thoroughly,  while 


MEMORY  357 

accumulated  repetitions  in  a  brief  period  produce  slight 
effect  and  one  that  quickly  disappears.  This  is  more 
certain  from  the  fact  that  divided  repetitions  leave 
much  more  persistent  effects  than  accumulated.  In 
general,  the  more  the  repetitions  are  divided  up  to 
one  every  third  day,  the  more  permanent  will  be  the 
learning. 

Rate  of  Repetitions.  —  Other  factors  that  affect 
learning  are  the  rate  at  which  the  material  is  read  and 
the  degree  of  acti\ity  or  the  degree  of  attention  given 
it.  The  rate  of  repetition  has  been  several  times  in- 
vestigated with  slightly  different  results.  Ebbinghaus 
first  asserted  that  the  more  rapid  the  rate,  the  quicker 
the  learning.  Ogden  modified  this  by  showing  that 
the  most  effective  rate  was  one  as  fast  as  could  be 
made  without  too  much  effort.  Part  of  this  differ- 
ence lay  in  the  fact  that  Ebbinghaus  used  the  time 
alone  as  a  measure  of  effectiveness ;  Ogden  employed 
both  time  and  the  number  of  repetitions.  Meumann, 
as  a  result  of  experience  gained  from  many  investiga- 
tions, concludes  that  the  best  rate  varies  with  the  individ- 
ual, the  material  to  be  learned,  and  the  familiarity  of  the 
learner  with  the  material.  It  is  best  to  read  relatively 
slowly  at  first  when  the  subject  matter  is  being  under- 
stood, and  more  rapidly  later,  up  to  the  point  where  the 
eft^ort  begins  to  distract. 

Active  Repetitions  More  Effective  than  Passive.  — 
The  effects  of  the  attention  of  the  reader  have  been  in- 
vestigated numerically  only  in  one  respect,  the  advan- 
tages of  passive  reading  as  compared  with  active  repeti- 
tion.    Witasek  made  experiments  to  determine  the  best 


358  FUNDAMENTALS    OF   PSYCHOLOGY 

combination  of  reading  with  attempts  to  repeat.  He 
found  that  the  most  satisfactory  result  was  obtained  when 
he  read  five  times  and  then  repeated  fifteen  times  from 
memory.  It  is  evident  that  attempting  to  repeat  from 
memory  requires  more  effort  and  will  hold  attention  much 
more  than  passive  reading.  It  should  be  said,  however, 
that  repeating  material  that  has  lost  its  freshness  in  an 
abstracted  state,  practically  without  attention,  will  give 
rise  to  learning  in  a  much  shorter  time  than  one  would 
think,  although  it  is  of  course  not  so  effective  as  repetition 
with  full  attention.  Still  another  factor  that  plays  an 
important  part  in  learning  is  the  intention  to  recall. 
Meumann  and  others  found  a  saving  of  50  per  cent  or 
more  if  series  were  repeated  with  the  expectation  of  being 
tested  on  them  later,  as  compared  with  similar  series  that 
were  learned  without  knowing  that  the  learning  was  to 
be  tested. 

Associative  Inhibition.  —  An  important  factor  in  pre- 
venting learning  is  the  presence  of  other  earHer  formed 
associations  with  the  syllables  to  be  learned.  Miiller  and 
Schumann  found  that,  if  two  associates  are  made  with  the 
same  syllable,  they  interfere  with  each  other,  and  the 
second  will  be  learned  with  greater  difficulty.  They 
demonstrated  this  by  learning  in  different  series  syllables 
a,  d,  g,  etc.,  first  with  b,  e,  h,  etc.,  and  then  another  con- 
nection ;  a  with  c,  d  with/,  g  with/,  etc.  It  was  found 
that  it  took  considerably  longer  to  learn  the  series  of 
syllables  when  other  syllables  had  already  been  con- 
nected with  them  than  when  learned  for  the  first  time. 
In  the  experiments,  the  syllables  to  be  relearned  were 
interspersed  irregularly,  so  that  the  association  with  the 


MEMORY  359 

old  positions  and  with  syllables,  that  were  near  but  not 
contiguous  in  the  first  connections,  should  not  aid  in 
the  relearning.  In  practical  Ufe  this  means  that  when 
one  thing  has  been  learned  with  another,  it  will  require 
a  longer  time  to  learn  it  with  a  second  than  if  it  had 
not  been  learned  with  the  first.  If  a  mistake  has  been 
made,  it  will  take  longer  to  correct  it  than  to  have 
learned  correctly  in  the  first  place.  But  where  several 
things  are  to  be  learned  in  the  same  connection,  it 
is  found  that  inhibition  ceases  to  be  effective  if  the 
first  is  thoroughly  learned*  before  the  second  is  begun. 
In  fact,  in  that  case  there  is  apparently  some  saving, 
since  the  famiharity  mth  the  old  saves  some  work  in 
learning  the  new.  Tliis  interference  of  earlier  formed 
associates  with  the  formation  of  new  ones  is  known  as 
the  associative  inhibition. 


Retention  and  Forgetting 

The  Rate  of  Forgetting.  —  The  investigations  of  the 
retention  of  associations  bear  largely  upon  the  rate  of  the 
disappearance  of  associations  with  time.  There  is  a  gen- 
eral tendency  toward  the  unlocking  of  associations  that 
begins  at  the  moment  of  reading  or  a  few  moments  later, 
and  goes  on  indefinitely.  Two  long  studies  have  been 
made  of  this  topic,  one  by  Ebbinghaus,  the  other  by 
Radossawljewitsch.  Their  results  may  be  compared 
in  the  table  on  the  foUowing  page.^ 

^  Ebbinghaus  considered  learning  complete  when  he  could  repeat  once ; 
Radossawljewitsch,  when  he  could  repeat  twice  without  mistake. 


360 


FUNDAMENTALS    OF   PSYCHOLOGY 


Length  of  Interval 

Per  Cent  Forgotten 

E 

R 

5  min 

20  min 

ihr 

8  hr.  45  min 

8hr 

1  day 

2  days 

6  days    

30  days 

1 20  days 

41.8 
55.8 
64.2 

66.3 
72.2 
74.6 
78.9 

2.5 
11.4 

29-3 

52.6 
32.2 
39-1 

50.7 
79.8 
97.2 

The  main  difference  is  to  be  seen  in  the  fact  that  Ebbing- 
haus  found  a  larger  percentage  forgotten  in  the  shorter 
periods.  Both  indicate  a  relatively  rapid  forgetting  at 
first,  and  a  relatively  slow  rate  in  the  longer  intervals. 
It  should  be  remembered  that  nonsense  syllables  were 
used  and  that  these  are  forgotten  much  more  quickly 
than  sense  material.  The  comparative  rapidity  of  for- 
getting during  the  first  few  days  suggested  to  Miiller  that 
there  might  very  likely  be  two  factors  to  take  into  con- 
sideration; first,  the  tendency  to  perseveration  or  the 
memory  after-image  which  diminishes  very  rapidly  and 
may  be  regarded  as  disappearing  in  the  first  two  days  or 
so,  and  the  associative  tendency,  which  in  accordance 
with  Jost's  law  is  to  be  conceived  as  increasing  in 
strength  for  two  days  or  more  and  then  decreasing 
in  strength  very  slowly.  For  most  purposes  the  in- 
crease in  the  strength  of  the  associative  tendency  is 
masked  in  the  total  curve  by  the  rapid  decrease  of 
the  perseverative  tendency,  but  later  the  decrease  in 


MEMORY  361 

the  strength  of  association  is  represented  by  the  curve 

of  forgetting  (Fig.  88). 


1       9  24  43  144 

Fig.  88.  —  Analysis  of  the  curve  of  forgetting  to  show  possible  cooperation 
of  perseveration  and  association.  The  full  Une  shows  the  course  of  forgetting 
after  Ebbinghaus,  the  dotted  line  the  conjectured  decrease  in  the  primary 
memory  (perseveration)  and  the  dashes  the  initial  increase  in  the  strength  of 
association  due  to  perseveration. 

Is  Forgetting  ever  Complete?  —  It  is  evident  from  these 
studies  that  associations  persist  when  there  is  little  imme- 
diate awareness  of  them,  when  one  cannot  even  bring 
them  back  by  an  associate  closely  connected  with  them ; 
when  they  can  be  detected  only  from  the  fact  that  they 
may  be  relearned  more  easily  than  if  they  had  not  pre- 
viously been  learned.  This  fact  has  given  rise  to  much 
discussion  as  to  whether  anything  is  ever  forgotten. 
The  discussion  arose  originally  from  the  fact  that  occa- 
sionally long-forgotten  events  from  a  remote  past  are 
recalled.  Coleridge  cites  the  case  of  a  girl,  a  servant  in 
the  house  of  a  pastor  who  was  accustomed  to  walk  up 
and  down  a  passageway  near  the  kitchen  where  she  was 
employed,  reciting  passages  from  Greek,  Latin,  and  He- 


362  FUNDAMENTALS    OF   PSYCHOLOGY 

brew  authors.  Some  years  later  in  a  delirium  of  fever 
she  was  heard  to  recite  strange  words  that  convinced 
her  attendants  that  she  was  possessed  of  a  devil.  The 
physician  wrote  them  down  and  traced  them  to  works  in 
the  possession  of  the  old  pastor,  now  some  years  dead. 
If  the  case  is  to  be  accepted,  memories  that  never  were 
consciously  developed  and  which  should  have  been  for- 
gotten if  they  ever  had  been  developed  may  still  be  lying 
dormant  in  the  nervous  system.  Numerous  other  cases 
may  be  cited  of  the  return  of  experiences  long  forgotten, 
usually  in  case  of  disease,  under  hypnosis,  or  in  similar 
abnormal  conditions.  These  cannot  be  taken  to  prove 
the  thesis  for  which  they  are  adduced,  but  they  may 
serve  to  reenforce  the  statement  that  experiences  leave 
their  effect  for  some  time  after  they  can  no  longer  be  re- 
called through  associations  of  ordinary  strength.  Not 
improbably  the  nervous  system  never  altogether  loses 
some  trace  of  them.  This  fact  is  of  more  importance  in 
explaining  recognition,  the  control  of  behef,  and  similar 
processes,  in  understanding  which  we  must  appeal  to 
the  effect  of  experiences  not  definitely  conscious  at  the 
moment,  than  as  a  contribution  to  the  understanding  of 
retention  and  recall.  Memories  constantly  grow  weaker 
at  a  rate  that  depends  upon  their  meaning  and  interest, 
and  gradually,  if  not  refreshed,  reach  the  stage  at  which 
they  cannot  be  revived. 

Recall 

Recall,  as  was  seen  in  the  earlier  chapter,  is  always 
through  association  under  the  control  of  the  wider  pur- 
pose of  the  moment  and  of  other  less  conscious  factors  that 


MEMORY  363 

constitute  the  mental  attitude  or  context.  To  recall 
any  old  event  it  is  necessary  to  have  some  idea  which  is 
in  some  way  connected  with  that  event  or  has  some  ele- 
ment in  common  with  it.  If  we  assume  the  possession  of 
a  definite  memory  with  a  large  number  of  connections, 
some  one  of  the  connections  must  become  conscious 
before  the  memory  itself  will  make  its  appearance. 
Usually  the  desire  to  remember  is,  either  itself  an  asso- 
ciate of  the  memory  desired,  or  they  are  both  connected 
with  a  common  idea.  Thus,  when  one  is  asked  a  question 
in  an  examination,  the  question  has  been  connected  with 
the  answer  and  serves  or  should  serve  to  recall  it.  The 
course  of  the  association  is  determined  by  the  setting,  the 
context  of  the  question  is  supplied  by  the  subject  in  which 
the  examination  is  held.  In  practical  Kfe  the  occasion 
for  the  recall  is  a  need  for  the  bit  of  knowledge.  A  face 
presents  itself  and  one  knows  that  the  name  will  be  needed 
when  it  becomes  necessary  to  make  an  introduction,  or 
one  is  reading  of  the  size  of  a  ship  in  metres  and  wonders 
how  long  it  is  in  feet  and  must  recall  the  table  of  equiva- 
lents. In  each  case  there  is  always  something  that  makes 
it  desirable  to  know  the  thing  to  be  recalled,  and  this  has 
also  been  associated  with  the  fact.  Not  all  associates 
of  an  idea  are  actually  recalled.  The  reason  for  this 
is  usually  that  the  right  context  is  lacking.  One  may 
read  of  the  length  of  the  ship  in  comparison  with 
other  ships  whose  lengths  are  also  given  in  metres, 
and  as  relative  size  is  all  that  is  necessary,  the  thought 
of  the  equivalent  does  not  occur  to  one.  The  mental 
attitude  or  need  of  the  moment  always  plays  a  pre- 
dominant part. 


364  FUNDAMENTALS   OF  PSYCHOLOGY 

Reproductive  Inhibition.  —  Interesting,  if  relatively 
unusual,  are  the  instances  in  which  one  has  occasion  for 
a  fact,  is  sure  that  it  is  known,  perhaps  well  known,  but 
in  which  one  cannot  recall  it.  One  may  be  asked  the 
name  of  a  famous  painter,  find  to  one's  astonishment  that 
it  cannot  be  recalled,  torture  one's  memory  for  it  as  one 
may.  Frequently  after  the  occasion  for  it  has  passed, 
it  will  come  back  without  the  least  difficulty,  often  when 
thinking  of  something  entirely  different.  Phenomena  of 
this  sort  seem  to  fall  under  the  head  of  reproductive  in- 
hibition that  was  established  by  Miiller  and  Schumann 
and  confirmed  by  Shepard  and  Vogelsonger.  It  was 
found  that,  when  two  syllables  were  learned  at  different 
times  in  connection  with  one  single  first  syllable,  there 
was  not  merely  an  obstruction  to  the  formation  of  the 
second  association  through  the  earlier  formation  of  the 
first,  but  also  an  inhibition  of  the  recall  of  both  when 
the  common  first  member  of  each  pair  was  shown.  The 
time  required  for  the  recall  of  either  is  much  increased 
while  the  percentage  of  times  that  either  will  be  recalled 
correctly  is  correspondingly  decreased.  It  seems  probable 
that  something  like  this  happens  in  the  moments  of 
blocked  recall  of  familiar  facts.  The  associations  must 
be  present  as  is  shown  by  the  later  recall,  but  apparently 
too  many  associates  strive  for  entrance,  and  each,  through 
some  neural  interference,  blocks  the  way  of  the  other.  It 
should  be  added  that  there  is  some  evidence,  obtained 
by  Bair^  in  his  experiments  on  learning  typewriting,  that 
when  a  series  of  associates  has  been  fully  learned  —  when 

^J.  H.  Bair,  The  Practice  Curve,  Psychological  Rev.  Men.  Sup- 
plements, No,  19. 


MEMORY  365 

one  keyboard  of  the  typewriter  has  been  thoroughly 
mastered  —  another  can  be  learned  in  less  time  and  there 
is  no  interference  between  them  on  recall.  Were  this 
not  true,  there  would  always  be  interference.  A  blocking 
of  recall  would  be  much  more  frequent  than  we  find  it, 
since  practically  every  bit  of  knowledge  has  many  asso- 
ciates that  might  be  recalled.  The  effect  of  the  purpose 
or  attitude  must  play  a  large  part  in  the  prevention 
of  inhibition.  WTien  the  context  favors  one  associate 
much  more  than  another,  the  way  is  cleared  for  it  and 
all  others  are  kept  from  interfering.  Interference  comes 
only  when  the  associations  are  not  fully  formed,  are 
relatively  weak,  or  no  strong  purpose  is  dominant. 

If  learning  and  retention  depend  upon  the  formation 
of  associations  and  the  degree  in  which  they  persist,  recall 
is  also  through  the  connections  that  are  formed  in  learn- 
ing. It,  too,  is  largely  a  mechanical  process,  dependent 
upon  the  relative  strength  of  the  associations,  guided 
only  by  the  context  and  the  purpose  of  the  moment. 
The  laws  that  have  been  given  ure  statements  of  the 
conditions  under  which  the  associations  may  be  formed 
with  greatest  strength  and  in  the  shortest  time,  together 
with  an  enumeration  of  the  factors  that  influence  re- 
tention and  the  course  of  the  forgetting,  and  the  laws 
of  recall.  All  this  is  of  value  in  practice,  since  the  laws 
hold  not  only  under  experimental  conditions  and  for 
nonsense  syllables,  but  also  for  sense  material  under 
conditions  of  ordinary  learning.  But  in  addition  to 
these  laws  that  apply  to  the  raw  materials  of  memory, 
the  fact  that  memory  ordinarily  deals  with  things  as 
real  and  with  ideas  that  have  meaning  and  logical  inter- 


366  FUNDAMENTALS   OF  PSYCHOLOGY 

connection  is  characteristic  of  the  process  and  is  an  im- 
portant element  in  determining  the  ease  or  difficulty  of 
the  part  processes.  The  most  important  influence  of 
meaning,  in  fact  what  first  gives  meaning  to  groups  of 
centrally  excited  sensations,  is  recognition.  By  recog- 
nition we  mean  that  the  idea  has  been  accepted  and  given 
a  place  in  the  experience  of  the  individual.  It  is  this 
in  large  measure  that  transforms  the  raw  materials  into 
ideas,  into  objects  and  events  that  have  a  real  relation 
to  the  past  life  of  the  individual  and  to  his  knowledge. 

Recognition 

Recognition  is  a  process  that  plays  a  very  large  part 
in  our  mental  life,  and  has  close  relations  with  reasoning 
as  well  as  with  perception  and  memory.  We  recognize 
objects  as  well  as  memories,  and  neither  an  object  nor  a 
memory  can  be  used  if  it  is  not  recognized,  or  understood, 
and  understanding  is  closely  related  to  recognition,  if 
not  a  form  of  recognition.  By  recognition  is  meant  the 
reference  of  an  event  or  object  to  some  earher  time  and 
place.  It  is  a  tagging  by  which  we  assign  the  experience 
a  place  in  our  earlier  life.  The  process  of  recognition  has 
a  number  of  degrees  and  several  forms.  What  may  be 
regarded  as  complete  recognition  is  an  assurance  of 
where  the  object  was  seen  before,  and  a  recall  of  all  the 
circumstances  of  that  earlier  experience.  This  is  called 
definite  as  opposed  to  indefinite  recognition.  In  the 
latter,  one  is  aware  that  the  thing  is  familiar  but  can 
assign  no  definite  place  to  it.  Many  faces  are  familiar 
which  recall  no  name  and  cannot  even  be  referred  to  a 


MEMORY  367 

specific  time  or  place.  This  indefinite  recognition  is 
ordinarily  due  to  slight  fainiKarity.  At  the  other  ex- 
treme, things  that  are  very  familiar  also  are  recognized 
but  referred  to  no  definite  place.  Here  the  recognition 
is  taken  for  granted.  This  happens  with  the  furniture 
of  a  well-known  room,  with  intimate  friends,  and  mth 
events  that  are  frequently  recalled.  It  is  an  implicit 
as  opposed  to  an  expKcit  recognition.  The  objects  are 
treated  as  if  known,  arouse  a  feeling  that  is  different  from 
that  aroused  by  strange  objects,  but  are  seldom  referred 
to  earlier  times  or  even  named. 

Another  reduction  from  complete  recognition  is  seen 
in  what  may  be  called  cognition,  assigning  a  new  event 
to  a  class  even  if  it  is  seen  for  the  first  time.  This  applies 
to  all  memories  and  to  all  objects  save  those  that  are 
absolutely  without  connection  with  our  past,  if  any  such 
present  themselves  to  the  educated  civiHzed  man.  One 
only  occasionally  recognizes  or  cares  to  recognize  a  dog, 
unless  it  be  his  own,  but  is  still  able  to  place  it,  to  give  its 
breed.  In  a  strange  place,  most  things  are  cognized,  are 
assigned  to  a  class,  although  none  may  be  recognized. 
Still  another  distinction  must  be  drawn  with  reference  to 
the  way  in  which  recognition  takes  place.  In  certain 
instances  one  can  see  how  the  recognition  goes  on.  A 
hauntingly  familiar  memory  makes  its  appearance,  but 
it  has  no  connections  and  can  be  given  no  place.  Grad- 
ually as  one  broods  over  it,  other  things  are  called  up  by 
it.  Then  suddenly  an  associate,  itself  familiar,  is  added 
to  it,  and  recognition  is  complete.  This  may  be  called 
mediate  as  opposed  to  the  immediate  recognition,  which 
is  much  more  usual.     As  will  be  seen,  each  of  these  types 


368  FUNDAMENTALS   OF  PSYCHOLOGY 

of  recognition  depends  upon  the  same  laws  and  has  the 
same  explanation ;  they  are  different  forms  of  the  same 
process. 

Influence  of  Meaning  on  Recognition.  —  Experimental 
study  of  recognition  shows  that  it  takes  a  different  course 
for  material  that  can  be  given  a  definite  connection  with 
soi^ething  that  is  itself  familiar  as  compared  with  ma- 
terial that  has  no  such  associates.  This  difference  can 
be  made  to  explain  apparent  contradictions  in  experi- 
mental results  obtained  by  two  of  the  early  experimenters 
in  this  field, — Wolfe  and  Lehmann .  B  oth  sought  to  deter- 
mine the  influence  of  the  lapse  of  time  upon  the  accuracy 
of  recognition.  Wolfe  worked  with  tones  which  could  be 
made  to  dift'er  by  as  little  as  four  vibrations,  and  had  a 
number  of  tones  at  his  command,  so  that  they  could  not 
be  readily  referred  to  a  class  or  given  a  distinguishing 
name.  He  found  that  capacity  to  recognize  diminished 
with  the  passage  of  time,  at  almost  the  same  rate  as  the 
ability  to  recall.  His  curve  showed  the  same  form  as 
Ebbinghaus'  curve  of  forgetting;  recognition  fell  off 
rapidly  at  first  and  much  more  slowly  later.  Lehmann 
used  gray  papers  of  different  shades.  At  first  he  used 
five  shades.  These  his  subjects  at  once  arranged  in  a 
series  and  gave  a  definite  name  to  each.  His  results 
showed  almost  no  tendency  to  diminution  of  accuracy 
with  the  passage  of  time.  At  first  the  judgments  in- 
creased slightly  in  accuracy  and  then  declined  slightly, 
but  there  was  no  approach  to  the  logarithmic  curve  ob- 
tained by  Ebbinghaus.  When  Lehmann  introduced  nine 
shades,  these  were  given  numbers  from  one  to  nine,  and 
the  curve  retained  the  same  form.     Later  investigations 


I 


MEMORY  369 

by  Angell  and  Hayward  and  by  Hayden  under  approxi- 
mately the  same  conditions  have  given  results  similar  to 
Lehmann's.  The  difference  in  the  results  obtained  by 
Wolfe  and  the  others  may  be  attributed  to  the  degree 
in  which  the  material  makes  possible  the  association  of  a 
word  or  other  fainiliar  symbol.  Where  no  such  symbol 
may  attach,  recognition  is  difi&cult,  and  ability  to  recog- 
nize vanishes  very  quickly.  When  the  symbol  may  be 
applied,  recognition  is  immediate  and  persists  for  some 
time  with  no  appreciable  diminution.  Back  of  the  assign- 
ment of  the  name  or  number  is  the  development  of  a  defi- 
nite image  or  notion  of  the  different  impressions  to  be 
recognized  that  shall  make  it  stand  out  for  itself,  that 
shall  make  it  a  fixed  standard. 

This  difference  between  the  results  obtained  by  Wolfe 
and  those  obtained  by  the  others  is  similar  to  the  dif- 
ference between  results  with  nonsense  and  sense  material. 
A  number  of  recent  experiments  by  Hollingworth,  Miss 
Mulhall,  Strong,  and  others  showed  the  same  difference 
in  ease  of  recognition  between  material  that  has  and  that 
which  has  not  meaning.  They  found  in  the  first  place 
that  recognition  was  much  more  certain  and  persisted 
longer  than  ordinary  recall.  It  was  from  two  to  three 
times  as  accurate  as  recall  when  advertisements,  pictures, 
words,  or  other  sense  material  was  used.  But  with  non- 
sense syllables,  recognition  had  very  little  if  any  advan- 
tage over  recall.  If  we  apply  this  to  our  other  problem, 
it  is  evident  that  recognition  of  meaningful  material  has 
a  very  great  advantage  over  recognition  of  nonsense 
material.  In  the  one  case  the  shades  of  gray  could  be 
immediately  connected  with  words  that  had  either  a 
2  B 


370  FUNDAMENTALS    OF   PSYCHOLOGY 

definite  meaning  acquired  long  before  these  experiments 
were  begun,  or  that  could  be  quickly  developed  for  the 
few  shades  used.  One  association  alone  needed  to  be 
formed  in  order  to  assure  recognition  in  each  experiment. 
Recognition  itself  required  no  more  than  a  decision 
whether  the  shade  offered  did  or  did  not  correspond  to  the 
standard  required.  In  Wolfe's  experiments,  no  standards 
were  present  at  the  beginning  and  none  could  be  readily 
developed  because  of  the  great  number  of  tones  used,  and 
the  slight  differences  in  pitch  that  were  available.  Here 
one  dealt  with  bare  association  processes  formed  during 
the  experiments  between  sensations,  neither  of  which  had 
a  meaning  of  its  own.  All  the  preparation  for  recogni- 
tion must  be  made  during  the  experiment,  while  in  the 
experiments  with  meaningful  material,  most  of  the 
preparation  was  completed  before  the  experiments  were 
begun.  Meaning,  then,  contributes  much  to  the  ease 
and  persistence  of  recognition. 

The  Association  Theory  of  Recognition.  —  Theories 
of  recognition  are  very  numerous  and  in  some  degree 
conflicting.  One  has  been  already  indicated,  the  placing 
of  the  unknown  through  association  with  the  known. 
This  can  be  traced  empirically  very  frequently.  One 
hears  the  title  of  a  book,  it  sounds  familiar  but  can  be 
given  no  place.  Gradually,  ideas  cluster  about  it  until  it 
is  placed  as  a  novel  by  so  and  so  read  on  the  boat  two 
years  ago,  or  it  may  be  it  is  remembered  to  be  the  book 
that  was  recommended  by  Jones  but  which  has  not  been 
read.  Similarly  with  objects.  This  bit  of  crystal  at 
first  seems  to  be  absolutely  unknown,  then  a  background 
grows  up  about  it,  you  remember  where  it  came  from ; 


MEMORY  371 

that  supplies  the  name  and  the  purpose  for  which  you 
obtained  it,  and  the  whole  recognition  is  complete. 
The  association  theory  assumes  that  all  recognition  is  of 
this  type,  and  that  in  the  cases  in  which  the  recognition 
is  indefinite  the  associates  are  present  and  give  their 
effect,  although  they  are  overlooked  or  do  not  come  to 
full  consciousness.  They  nevertheless  provide  the  mark 
of  familiarity,  give  a  color  to  consciousness  that  is 
accepted  as  a  warrant  for  the  belief  that  the  idea  or  object 
has  been  experienced  before.  Another  theory  with 
many  adherents  is  that  the  feeling  of  familiarity  comes 
from  slight  movements  awakened  by  the  stimulus  or 
image.  This  is  approximately  the  same  theory  as  the 
other,  except  that  the  processes  aroused  are  motor  rather 
than  sensory.  The  idea  arouses  refiexly  some  move- 
ment, slight  or  more  intense,  and  this  constitutes  the 
basis  of  the  assurance  that  the  object  has  been  seen  before. 
The  movements  themselves  are  not  recognized,  but  be- 
cause of  their  arousal  the  familiarity  attaches  at  once  to 
the  object.  The  best  instance  of  this  is  to  be  found  in  the 
feeling  of  '  at  homeness  '  that  comes  with  the  use  of  an 
old  tool  or  instrument  when  one  comes  back  to  it  after 
a  period,  as  compared  with  the  feeling  of  a  strange  one, 
even  if  it  is  of  the  same  pattern.  The  habits  that  have 
been  developed  in  its  use  are  suited  to  it,  and  the  pleasant 
feehng  of  familiarity  results. 

Recognition  an  Immediate  Quality.  —  Another  group 
of  theories  starts  with  the  assumption  that  recognition 
is  an  immediate  experience  that  cannot  be  analyzed  or 
explained,  but  must  either  be  accepted  as  a  given  fact 
or  be  speculated  about  in  general  terms.     The  more  defi- 


372  FUNDAMENTALS   OF  PSYCHOLOGY 

nite  of  these  theories  asserts  that  recognition  comes  be- 
cause of  the  pleasure  that  attaches  to  the  familiar  expe- 
rience as  compared  with  the  unpleasantness  or  neutral 
quality  of  the  unknown.  The  pleasure  is  explained  as 
the  result  of  an  instinct.  The  known  is  pleasant,  since 
one  always  makes  an  immediate  response  to  it.  If 
harmful,  one  can  avoid  it  immediately ;  if  beneficial,  it 
is  pleasant  in  and  of  itself.  The  objection  to  the  theory 
is  based  primarily  on  fact.  Not  all  cases  of  recognition 
are  pleasant,  certainly  not  all  pleasant  things  are  familiar. 
Another  theory  in  this  group  asserts  that  familiarity  is 
an  immediate  conscious  experience,  even  more  primary 
than  either  sensation  or  association.  This  theory  has  a 
chance  if  all  others  fail.  The  same  objections  hold  to  it 
as  to  nativism  in  space.  It  gives  up  the  problem  without 
attempting  an  explanation. 

The  evidence  so  far  accumulated  favors  the  association 
theory  in  some  form.  Recognition  of  the  indirect  type 
can  be  traced  to  associations.  In  the  direct  or  imme- 
diate type,  things  that  have  many  associates  are  readily 
recognized,  while  nonsense  material,  that  is  material 
without  associates,  is  recognized  with  difficulty,  is  recog- 
nized no  more  easily  than  it  is  remembered.  Recognition 
is  aided  also  by  two  of  the  factors  that  aid  association. 
Meyer  showed  that  recognition  of  nonsense  syllables 
was  more  accurate  when  a  syllable  with  which  it  had 
previously  been  associated  was  shown,  just  before  the 
syllable  to  be  recognized  was  presented.  It  has  been 
shown,  too,  that  recognition  is  quicker  and  more  accurate 
if  the  individual  is  in  the  proper  attitude  toward  the  ob- 
ject to  be  recognized  just  before  it  is  shown.     Just  as  in 


MEMORY  373 

everyday  life,  if  one  meet  an  old  acquaintance,  one  is 
very  much  more  likely  to  recognize  him  if  one  has  been 
thinking  about  the  place  where  he  was  known,  than  if 
he  appears  without  any  preparation.  These  four  facts 
together  indicate  that  association  and  recognition  are 
very  closely  related.  Recognition  always  comes  when 
associates  are  aroused,  and  where  associates  are  not 
overtly  present,  experiments  indicate  that  conditions 
which  favor  the  formation  of  associates  or  recall  by  asso- 
ciation also  favor  recognition. 

Meaning  and  Recognition.  —  In  any  statement  of  the 
association  theory  of  recognition,  it  must  be  recognized 
that  the  associates  must  be  themselves  familiar  or  the 
process  will  not  be  complete.  Sometimes  several  links 
are  necessary  before  a  familiar  associate  presents  itself. 
This  familiarity  that  attaches  to  these  added  associates 
and  also  to  the  objects  recognized  immediately  is  itself 
due  to  associates.  The  difference  between  the  mediate 
and  the  immediate  is  another  expression  of  the  difference 
between  the  two  sorts  of  recognition  that  distinguished 
the  methods  used  by  Wolfe  and  by  Lehmann.  One 
must  get  back  to  some  established  type,  to  something  that 
has  been  used  so  frequently  and  recalled  so  often  that  it 
has  become  firmly  estabhshed  and  thoroughly  familiar. 
These  are  accepted  at  once  and  without  question.  They 
are  the  types  that  we  found  necessary  to  explain  percep- 
tion, and  are  also  the  concepts  that  play  an  essential  part 
in  reasoning.  Probably  these  fixed  points  of  reference 
for  our  knowledge  are  also  established  and  receive  recog- 
nition through  the  numerous  associates  that  they  tend 
to  arouse  but  which  do  not  become  explicit.     Your  own 


374  FUNDAMENTALS    OF   PSYCHOLOGY 

name,  to  take  an  extreme  case,  is  established  more  firmly 
than  the  name  of  another  because  of  the  number  of  times 
it  has  been  associated  with  yourself  and  with  other  expe- 
riences. Events  that  serve  as  landmarks  in  all  memory 
become  such  from  the  number  of  associates  that  have 
been  made  with  them  at  the  time,  and  through  their 
frequent  recall  in  different  connections.  When  an  event, 
that  is  at  first  unplaced,  can  be  attached  to  one  of  these 
firmly  established  incidents,  it  at  once  takes  on  something 
of  its  familiarity,  in  the  same  way  that  assignment  of 
the  name  was  all  that  was  necessary  in  Lehmann's  experi-' 
ments  to  constitute  recognition  of  the  shade.  Probably 
the  feeling  of  familiarity  is  due  in  these  very  frequently 
repeated  objects  and  events  to  partially  open  association 
paths  that  give  recognition  without  any  definite  recall 
of  the  associated  events.  In  case  the  object  is  familiar 
but  cannot  be  definitely  placed,  it  is  probable  that  there 
are  also  partially  open  association  paths,  but  they  do  not 
lead  to  the  meaningful  object  or  to  the  fixed  landmark. 
The  feeling  is  present  with  nothing  to  fix  the  experience. 
Similarly,  in  certain  cases  in  which  the  recognition  is 
false,  when  one  sees  an  individual  who  seems  familiar 
but  on  speaking  finds  that  he  is  not  an  acquaintance,  it 
is  probable  that  something  in  the  person  suggests  another 
or  calls  up  associates  that  are  misplaced.  Here  the 
associates  give  the  feeling  without  even  warrant  in  fact. 
In  short,  partially  open  association  paths  give  the  feeling 
of  familiarity  when  recognition  is  not  complete  and  even 
when  the  recognition  is  not  objectively  true.  In  the 
constant  recognition  of  everyday  objects,  famUiarity 
is  the  rule,  strangeness  the  exception.     In  consequence, 


MEMORY  375 

the  fact  of  recognition,  as  well  as  how  it  takes  place,  is 
seldom  noticed.  Only  the  unknown  attracts  attention. 
Recognition  and  Cognition.  —  Recognition  is  largely 
aided  by  the  t}'pes  that  were  found  to  play  so  large  a 
part  in  perception,  and  also  by  meaning,  a  process  funda- 
mental to  thinking  of  all  t^pes.  The  part  played  by  the 
type  and  by  meaning  may  be  seen  more  clearly  in  the 
more  generalized  form,  cognition.  Here  objects  are 
referred  to  classes  rather  than  to  particular  times  or  places. 
It  is  more  frequent  than  recognition.  We  are  constantly 
referring  all  objects  that  come  under  our  notice  to  a  class. 
Natural  objects  are  named,  tools  related  to  their  uses, 
people  are  assigned  to  different  races  or  classes  when  they 
are  not  acquaintances.  This  process  of  cognition  differs 
from  recognition  only  in  that  there  is  no  reference  to  the 
earlier  experience  of  the  individual,  no  awareness  that  the 
thing  has  ever  before  been  seen.  Except  for  determining 
ownership  of  objects  and  for  our  relations  with  people, 
it  is  seldom  that  we  need  to  do  more  than  cognize. 
Cognition  difi'ers  from  recognition  only  in  that  the  ref- 
erence is  to  some  class  only,  some  type  of  objects,  with 
no  reference  to  personal  knowledge.  The  process  in- 
volves the  same  factors,  there  is  always  a  general  notion 
as  the  point  of  attachment,  but  this  has  a  more  or  less 
marked  series  of  associations  that  irradiate  from  it  to 
give  appreciation  of  its  use,  or  of  its  special  character- 
istics. In  almost  every  respect  it  is  like  the  t>pe  or 
concept  that  we  saw  to  be  aroused  in  perception,  and  to 
constitute  what  we  accept  as  the  real  object.  Cognition 
is  a  reference  of  the  particular  object  or  memory  image  to 
a  similar  typical  object  or  class.     Memory  is  like  percep- 


376  FUNDAMENTALS    OF   PSYCHOLOGY 

tion  in  that  it  deals  with  real  objects  or  concepts,  rather 
than  with  mere  centrally  excited  sensations. 

Meaning  in  Learning.  —  Meaning  is  not  only  a  factor 
in  making  recognition  possible  but  is  also  an  important 
factor  in  all  learning.  The  meaning  that  the  material 
to  be  learned  has  for  the  individual  determines  in  very 
large  degree  how  quickly  it  may  be  learned  and  how  long 
it  shall  be  retained.  The  difference  in  the  amount  of 
time  required  for  learning  and  the  degree  of  retention 
between  sense  and  nonsense  material  is  very  striking. 
This  may  be  seen  both  in  primary  memory  and  in  learning 
long  series.  Ebbinghaus  found  that  school  children  could 
give  only  five  of  seven  nonsense  syllables,  while  of  a 
sentence  of  38  words  containing  seventeen  separate  ideas, 
they  could  remember  fifteen  of  the  ideas.  For  himself 
he  found  that  with  the  same  number  of  repetitions  he 
could  remember  eight  or  nine  times  as  much  of  simple 
poetry  as  of  nonsense  syllables.  Meumann  obtained 
slightly  smaller  values,  7-9  nonsense  syllables,  13  words  or 
numbers,  20  words  of  a  poem,  and  '24  of  philosophical 
prose. 

Meaning  not  only  aids  in  learning  but  also  assures  a 
greater  persistence  of  the  material  that  is  learned.  The 
material  learned  is  much  less  readily  forgotten.'  Ebbing- 
haus demonstrated  the  fact  for  rote  memory  of  verse. 
In  some  of  his  earlier  experiments  he  used  a  translation  of 
Byron's  "  Don  Juan."  After  twenty-two  years,  he  found 
that  he  could  detect  a  saving  of  7  per  cent  in  the  time 
required  for  relearning  stanzas  as  compared  with  learning 
new  stanzas.  After  seventeen  years  there  was  a  saving 
of  20  per  cent  in  relearning  stanzas  which  had  originally 


MEMORY  377 

been  learned  on  four  successive  days.  This  is  to  be  com- 
pared with  a  saving  of  20  per  cent  for  nonsense  syllables 
at  the  end  of  thirty  days.  The  retention  of  ideas  is  still 
more  complete.  General  principles,  or  even  interesting 
events,  are  frequently  recalled  after  the  greater  part  of 
a  lifetime.  Here,  however,  there  is  usually  repetition  or 
recall  in  the  intervening  years. 

Meaning  Due  to  Grouping  and  to  Reference  to  Systems 
of  Experiences.  —  Two  reasons  may  be  found  for  the 
greater  ease  of  learning  meaningful  material.  One  is 
that  to  gain  meaning  the  different  partial  experiences 
must  be  grouped  about  a  single  centre,  must  be  combined 
into  units,  and  these  units  are  then  remembered  practi- 
cally as  single  elements.  In  some  recent  investigations 
of  a  lightning  calculator.  Dr.  Ruckle,  G.  E.  Miiller  found 
that  an  essential  element  of  his  ability  to  make  calcula- 
tions very  quickly  lay  in  the  capacity  for  remembering 
figures,  and  that  this  in  turn  was  due  to  an  ability  to 
unite  the  figures  into  small  groups.  Ruckle  could  retain 
and  repeat  in  any  order  forty-nine  digits.  He  saw  them 
arranged  in  seven  columns  of  seven  digits  each.  The 
seven  series  seemed  to  count  for  him  as  seven  single 
units.  A  second  element  in  acquiring  meaning,  well 
illustrated  by  this  same  investigation,  is  the  attachment 
of  the  thing  to  be  remembered  to  elements  of  experience 
already  firmly  fixed,  —  an  interpretation  in  the  light  of 
old  knowledge.  Ruckle  related  many  of  the  numbers 
that  he  could  remember  to  combinations  of  numbers  with 
which  he  was  already  familiar.  Thus  he  could  remember 
451,697,  since  it  was  made  up  of  the  multiples  of  two 
prime  numbers:    451  =  11  x  41,  697  =  17  x  41.     Six 


378  FUNDAMENTALS   OF  PSYCHOLOGY 

hundred  and  twenty-four  was  easy,  since  it  is  the  square 
of  2  5  minus  i .  ^  With  a  large  acquaintance  with  numbers, 
learning  new  ones  was  relatively  easy.  All  material  that 
has  meaning  has  these  two  qualities.  It  is  combined  into 
relatively  small  groups,  and  these  groups  are  used  over 
and  over  again  until  they  constitute  practically  a  unit  and 
they  are  learned  in  different  connections  until  firmly  es- 
tablished and  can  be  recalled  by  many  other  experiences. 
When  anything  has  meaning,  it  is  already  connected  with 
something  that  is  a  part  of  the  fundamental  intellectual 
equipment  of  the  individual.  In  this,  to  have  meaning 
and  to  be  recognized  or  cognized  are  approximately 
identical.  Thus,  recognition  we  saw  to  consist  in  attach- 
ing to  the  object  or  idea  that  is  to  be  recognized  some 
mark  in  itself  familiar.  The  permanency  of  recognition, 
then,  becomes  the  permanency  of  the  older  acquirement. 
In  learning  material  that  has  meaning,  the  same  factor  is 
even  more  prominent.  When  the  meaning  of  anything  is 
understood,  it  is  by  that  very  fact  united  to  the  already 
familiar,  becomes  an  instance  under  a  general  law  or  a  gen- 
eral class,  and  that  gives  it  in  large  degree  the  permanence 
of  the  general  law.  The  meaningful  materia],  by  virtue 
qf  the  fact  of  having  meaning,  will  then  be  sure  to  belong 
to  a  larger  group  and  so  become  easier  to  learn,  and  will 
also  be  connected  with  something  that  is  already  known 
and  which  permits  the  new  to  be  understood.  These 
two  characteristics  alone  would  go  far  toward  explaining 
the  advantage  for  learning  of  sense  material. 

The  importance  of  meaning  can  be  seen  to  still  better 
advantage  in  the  type  of  learning  most  frequently  prac- 
*Zeitschrift  f.  Psychologic  Erganzungsbd.  5  pp.  215  ff. 


MEMORY  379 

tised  in  adult  life,  learning  the  substance  without  the 
words.  In  this  there  must  be  some  connection  with  a 
wider  knowledge,  or  nothing  can  be  retained.  Almost 
anything  that  is  understood  can  be  retained  for  a  little 
time,  and  to  understand  is,  in  essence,  to  connect  the  new 
with  the  pre\'iously  organized  knowledge.  The  degree 
of  retention  depends  in  part  upon  frequency  of  repetition 
of  the  ideas,  but  much  more  upon  the  number  of  different 
ways  in  which  the  new  is  linked  to  the  old,  and  thus  to 
the  completeness  with  which  it  is  understood.  While 
the  process  of  understanding  is  more  important  on  the 
whole  than  the  formation  of  discrete  associations,  both 
must  be  present  in  some  degree.  Cleaning  has  a  basis 
in  association,  as  has  been  pointed  out,  and,  on  the  other 
hand,  frequent  repetition,  even  of  nonsense  syllables, 
tends  to  give  them  some  meaning,  however  slight.  For 
practical  purposes  they  are  usually  opposed.  In  rote 
learning  only  the  associates  between  the  elements  are 
considered ;  in  sense  material  the  connections  with  the 
more  general  knowledge  is  emphasized.  When  one  is 
learning  by  rote,  the  meaning  of  the  material  may  be  lost 
sight  of ;  in  sense  learning,  the  words  may  be  altogether 
neglected.  Either  can  be  trained  at  the  expense  of  the 
other.  Individual  differences  in  the  use  of  one  or  the 
other  are  matters  of  training,  and  it  is  possible  to  acquire 
the  abihty  to  use  either  at  will. 

Individual  Differences  in  Memory.  —  Not  merely  is 
there  a  difference  in  the  degree  to  which  rote  and  sense 
memory  may  be  used,  but  there  are  differences  in  the  ca- 
pacity of  learning  in  general  and  in  the  aptitude  for  learn- 
ing different  kinds  of  material.    One  of  the  most  discussed 


380  FUNDAMENTALS   OF  PSYCHOLOGY 

is  the  difference  between  quick  and  slow  learners .  Ebbing- 
haus  asserts  that  there  is  a  law  of  compensation  in  learning 
in  that,  if  one  learns  slowly,  one  also  forgets  slowly.  The 
instances  chosen  prove  only  that  there  is  a  greater  per- 
centage of  saving  for  the  slower  learners,  but  the  number 
of  repetitions  required  for  relearning  is  least  with  the 
quick  learner,  and  not  so  very  much  greater  for  those 
who  learned  more  slowly  in  the  beginning.  Later 
experiments  indicate  that  the  quick  learner  is  more  effec- 
tive in  every  respect.  At  the  best,  then,  the  slow  learner 
has  an  advantage  only  in  the  percentage  remembered, 
not  in  the  amount  that  may  be  recalled  by  associates  or 
in  the  time  required  for  relearning.  In  several  of  the 
cases  given,  a  quick  learner  would  learn  and  relearn 
twenty-four  hours  later  in  fewer  repetitions  than  the  slow 
learner  required  for  the  first  learning. 

Dependence  upon  Age.  —  The  dependence  of  memory 
upon  age  is  fairly  well  made  out.  Measured  either  by 
the  memory  span,  the  quickness  of  learning,  or  the  imme- 
diate retention,  memory  increases  gradually  to  thirteen, 
then  improves  very  rapidly  to  sixteen,  and  then  more 
slowly  to  a  maximum  at  twenty- two  to  twenty-five, 
then  apparently  persists  approximately  unimpaired 
throughout  Hfe,  or  at  least  until  the  onset  of  senile  decay. 
Meumann  grants  that  children  may  retain  material  once 
learned  rather  better  than  adults,  a  fact  which  accounts 
for  the  large  percentage  of  our  memories  that  come  from 
early  childhood,  but  both  immediate  memory  and  ease 
of  learning  are  greatest  after  maturity  has  been  attained. 
Another  factor  that  may  be  regarded  at  any  moment  as 
an  individual  difference,  although  it  may  depend  upon 


MEMORY  381 

habit,  is  the  tendency  to  remember  meanings  or  to 
remember  by  rote.  This  accounts  for  part  of  the  ap- 
parent advantage  of  children.  They  are  accustomed  to 
learn  by  rote,  and  for  that  reason  do  it  relatively  better 
than  do  adults,  who  are  at  once  lost  in  the  meaning  and 
find  difficulty  in  forcing  themselves  to  attend  to  the 
words.  This  can  of  course  be  cultivated  either  way, 
and  adults  who  have  cultivated  rote  learning  have  an 
advantage  in  this  also. 

Dependence  upon  Types  of  Imagery.  —  Still  another 
more  truly  indi\idual  characteristic  is  to  be  found  in  the 
dependence  of  memory  upon  sensorial  type.  An  indi- 
vidual of  a  visual  t}'pe  is  probably  more  successful  in 
remembering  words,  colors,  landscapes,  ■  and  similar 
material ;  an  individual  of  the  auditory  t}pe,  in  musical 
memories  of  all  sorts  and  for  the  order  of  material  that  is 
learned.  Which  t^pe  is  absolutely  the  best  is  not  known, 
since  investigations  have  not  extended  to  a  sufficiently 
large  number  of  individuals.  ]\Ieumann  asserts  that  the 
visual  memory  is  best  for  the  retention  of  the  elements, 
but  that  the  motor-auditory  obtains  a  more  accurate 
grasp  of  the  whole.  In  the  work  of  the  arithmetical 
prodigies  or  lightning  calculators,  differences  in  memory 
t}pe  play  a  considerable  part  in  determining  the  character 
of  their  feats.  Two  that  have  been  studied,  Diamandi 
and  Dr.  Ruckle,  were  visual  in  t}^e,  and  one,  Inaudi,  was 
auditory-motor.  The  motor  t}^e  did  not  lend  itself 
to  the  reversal  of  operations,  but  with  simpler  processes 
was  much  quicker  than  the  visual.  On  the  whole  the 
motor  memory  was  quicker  as  far  as  it  went,  but  much 
less  flexible  than  the  visual  memory.     When  space  factors 


382  FUNDAMENTALS   OF  PSYCHOLOGY 

entered,  the  visual  far  outstripped  the  motor-auditory. 
These  are  but  illustrations  of  differences  in  capacity  that 
depend  upon  the  memory  type.  Much  remains  to  be 
done  before  we  can  state  all  the  differences. 

Memory  Training.  —  If  one  be  asked  how  to  learn  to 
the  best  advantage,  or  how  to  improve  one's  memory  or 
capacity  for  remembering,  the  best  answer  is  to  apply 
the  rules  given  under  the  different  heads  of  this  chapter. 
If  material  is  to  be  learned  by  rote,  it  is  essential  that 
there  should  be  a  large  number  of  repetitions.  In  any 
case  the  repetitions  should  be  divided  over  as  many  days 
as  possible  and  should  also  be  made  by  the  whole  method, 
and  not  part  by  part  or  bit  by  bit.  The  units  should  be 
grouped  into  wholes  as  far  as  possible,  since  this  grouping 
reduces  the  work  that  must  be  done  in  learning.  Above 
all,  however,  wherever  the  material  to  be  learned  has  any 
meaning,  it  is  essential  to  understand  it.  Material  under- 
stood is  more  than  half  learned.  In  the  process  of  under- 
standing, it  is  well  to  approach  the  material  from  as 
many  different  points  of  view  as  possible.  The  greater 
the  number  of  points  of  attachment,  the  more  thorough 
is  the  understanding,  and  also  the  greater  the  number 
of  connections  by  which  to  arouse  the  memory  in  recall. 
Where  matter  is  to  be  learned  by  rote  as  well  as  in  sub- 
stance, it  is  well  to  make  two  or  three  repetitions  to  under- 
stand the  material,  and  then  to  proceed  to  commit  to 
memory  by  repetition.  It  is  essential  also  to  attempt 
to  repeat  unaided  as  soon  as  possible.  Usually  after  four 
or  five  repetitions,  a  free  recall  should  be  begun  and 
frequent  tests  made  of  the  parts  that  are  least  well  re- 
called. 


MEMORY  383 

Memory  Systems.  —  Numerous  attempts  have  been 
made  since  classical  time  to  develop  methods  of  aiding 
memory.  Latin  orators  made  use  of  the  device  of  pic- 
turing their  orations  upon  the  walls  of  different  rooms  of 
a  house,  one  part  on  each  wall  of  a  room,  and  larger  units 
in  the  same  room.  As  they  proceeded,  they  would  pic- 
ture themselves  as  walking  through  the  house  and  reading 
their  various  headings  from  the  walls.  A  more  modern 
form  of  mnemonics,  but  one  that  goes  back  several  centu- 
ries, consists  in  forming  series  of  links,  based  upon  chance 
associates  between  any  two  things  that  are  to  be  recalled 
together.  Thus  one  may  remember  that  A  is  the  Greek 
letter  delta  by  the  series  :  triangle,  pyramid,  Nile,  Delta. 
Or  it  may  be  remembered  that  Denver  is  the  capital  of 
Colorado  through  the  Hngo,  Colorado,  dodo,  bird,  dense 
air,  Denver.  Similar  connections  are  made  by  these 
systems  between  any  two  facts  that  are  to  be  connected. 
Obviously  any  scheme  of  this  kind  will,  in  the  long  run, 
prove  more  harmful  than  helpful,  as  it  involves  making 
four  or  five  associates  where  only  one  is  needed,  and  the 
others  are  Hkely  to  develop  inhibitions  as  well  as  waste 
time.  It  is  much  better  to  trust  to  forming  the  associa- 
tions directly,  and  better  still,  if  connections  are  needed, 
to  base  them  upon  some  fundamental  general  principle. 
The  system  of  the  sciences  is  from  one  point  of  \'iew 
merely  a  big  mnemonic  system,  a  means  of  bringing  a 
large  number  of  isolated  facts  into  connection  with  each 
other  in  some  logical  way.  To  make  use  of  that  as  a 
means  of  remembering  is  to  follow  a  plan  that  has  been  de- 
veloped by  the  best  minds  of  all  times,  rather  than  some 
chance  scheme  that  has  been  hit  upon  by  a  charlatan. 


384  FUNDAMENTALS   OF  PSYCHOLOGY 

Memory  Training.  —  A  question  of  practical  as  well 
as  theoretical  interest  is  whether  exercises  in  learning 
may  be  said  to  train  mem.ory,  whether  training  in  learning 
one  sort  of  material  or  under  one  set  of  conditions  is 
transferred  to  learning  some  other  material  or  under 
another  set  of  conditions.  All  experiments  in  learning 
under  experimental  conditions  show  important  improve- 
ment with  practice.  There  is  also  some  improvement 
when  one  practises  on  nonsense  syllables  and  tests  by  the 
capacity  to  learn  sense  material  or  by  any  form  of  rote 
learning.  It  has  sometimes  been  held  that  memory  was 
something  that  could  be  trained  in  and  of  itself  Kke  a 
muscle.  Practically  all  modern  evidence  favors  the^ew 
that  the  improvement  is  really  in  the  methods  that  are 
used  in  learning.  One  becomes  accustomed  to  attending 
under  the  pecuHar  conditions  of  the  laboratory ;  one  forms, 
consciously  or  unconsciously,  good  habits  of  study,  learns 
to  read  with  the  intention  of  remembering,  and  these 
habits  may  be  carried  over  to  any  other  material  with 
advantage.  From  what  we  know,  this  is  the  only  sense 
in  which  memory  can  be  improved  in  any  general  funda- 
mental way,  and  this  is  sufficient  to  account  for  the 
improvement  actually  demonstrated.  Another  form  of 
improvement  can  be  noticed  in  connection  with  sense 
material,  a  form  that  comes  without  effort  and  is  a  neces- 
sary part  of  all  learning.  This  is  the  increase  in  ability 
to  understand  which  develops  with  increased  knowledge. 
As  knowledge  accumulates  and  is  well  ordered,  more 
points  of  reference  develop  and  each  of  these  serves  as  a 
peg  upon  which  new  facts  may  be  hung.  Just  as  Dr. 
Ruckle's  new  numbers  could  be  referred  to  numbers 


MEMORY  385 

known  as  the  squares  and  cubes  of  small  numbers,  and 
could  be  remembered  in  terms  of  those,  so  a  new  fact  that 
can  be  given  a  place  in  the  system  of  knowledge,  as  an 
instance  of  a  familiar  principle,  is  readily  remembered. 
This  system  of  knowledge  grows  with  learning,  and  as 
each  addition  to  it  is  preparation  for  new  acquirement, 
all  learning  may  be  said  in  this  sense  to  train  the  memory. 
Imagination.  —  Imagination  is  a  word  that  is  con- 
stantly heard  in  popular  speech  and  has  been  much  used 
by  psychologists.  Unfortunately,  however,  the  usage 
has  been  so  varied  that  it  is  difficult  to  select  one  that 
can  be  said  to  be  general.  It  has  connections  with  both 
memory  and  reasoning.  We  speak  of  constructive  imag- 
ination as  approximately  the  same  as  reasoning,  and  of 
reproductive  imagination  as  if  it  had  about  the  same 
function  as  memory.  Many  recent  writers  use  it  to  indi- 
cate the  primary  functions  discussed  in  connection  with 
centrally  excited  sensations.  This  goes  back  to  the  pri- 
mary meaning  of  the  term  as  a  process  of  forming  images. 
So  far  as  our  needs  are  concerned,  imagination  may  be 
used  to  designate  those  mental  processes  in  which  the 
resulting  idea  is  not  referred  to  a  definite  period  in  the 
past  as  in  memory,  and  is  not  regarded  as  a  true  construc- 
tion and  guide  to  conduct  as  are  the  results  of  reasoning. 
The  laws  of  revival  of  the  old  experiences  which  hold  for 
memory  hold  also  for  imagination,  but  the  product  is 
not  recognized ;  on  the  contrary,  it  is  held  to  refer  to  no 
time  or  place  in  the  past,  to  represent  no  actual  event. 
As  compared  with  reasoning,  its  results  are  not  accepted 
as  true  absolutely,  but  are  assured  to  be  possible  only 
under  certain  conditions  not  themselves  accepted  as 
2  c 


386  FUNDAMENTALS    OF   PSYCHOLOGY 

likely.  In  other  words,  it  is  assigned  but  a  limited  and 
conditional  truth.  In  any  case,  imagination  differs  from 
memory  only  in  the  attitude  taken'  toward  the  final 
product,  is  practically  identical  with  it  in  the  conditions 
that  determine  its  origin.  To  anticipate,  it  may  be  said 
that  it  differs  from  reason  also  only  in  the  attitude  that 
is  taken  towards  the  outcome.  One  believes  when  one 
reasons ;  one  need  not  believe  when  one  imagines. 

REFERENCES 

COLVIN :  The  Learning  Process. 
Meumann  :  The  Psychology  of  Learning. 


CHAPTER  XI 

REASONING 

Mental  operations  are  not  restricted  to  receiving  im- 
pressions from  the  outside  world  and  to  recalling  experi- 
ences received  at  some  earlier  time.  Quite  as  important, 
in  many  respects  much  more  important,  are  the  operations 
in  which  experience  already  accumulated  is  used  in  the 
anticipation  of  future  experiences,  in  understanding  and 
organizing  earlier  experiences,  and  in  the  development  of 
new  constructions,  mental  and  physical.  Were  these  con- 
structive acti\dties  to  be  eliminated,  much  that  is  pecul- 
iarly human,  all  that  makes  progress  possible,  would  dis- 
appear. Reasoning  in  its  wider  applications  covers  all 
of  the  constructive  processes.  It  organizes  the  past  in 
preparation  for  the  future,  it  makes  mental  constructions 
that  may  later  be  developed  through  action  into  real 
productions.  Fut  while  the  end  of  reasoning  is  con- 
struction, it  builds  upon  the  materials  that  have  been 
provided  by  perception  and  memory.  Many  of  its  fun- 
damental laws  are  similar  to  those  that  have  already  been 
developed.  Most,  if  not  all,  reasoning  is  concerned  with 
problem  sohdng ;  reasoning  proper  is  restricted  to  solv- 
ing problems  in  thought  alone,  although  the  problem  once 
solved  may  and  usually  does  prepare  for  real  construc- 
tion.     The  results  attained  in  thought  lead  directly  to 

3&7 


388  FUNDAMENTALS   OF   PSYCHOLOGY 

and  control  action.  We  may  for  convenience  distinguish 
two  types  of  problems,  —  those  that  have  reference  only  to 
the  purely  mental  constructions,  to  the  mere  understand- 
ing of  the  world,  and  those  which  go  beyond  in  preparing 
the  way  for  action.  This  distinction  is  of  more  impor- 
tance in  theory  than  in  practice,  since  both  sets  of  prob- 
lems are  solved  in  the  same  way.  The  distinction  comes 
only  after  the  problem  is  solved,  in  the  use  that  is  made 
of  the  solution.  In  the  one,  we  are  content  with  a  mere 
understanding  of  the  problem ;  in  the  other,  we  prepare 
for  the  attainment  of  some  practical  end. 

Reasoning  Involves  Meaning.  —  One  factor  common 
to  all  reasoning,  as  it  is  to  so  many  of  the  processes  al- 
ready discussed,  is  meaning.  We  must  attempt  to  bring 
together  the  evidence  that  has  gradually  been  developing 
through  the  earlier  chapters  as  to  w^hat  meaning  is. 
Perhaps  the  greatest  obstacle  to  determining  what  mean- 
ing is  arises  from  the  fact  that  we  are  usually  not  di- 
rectly conscious  of  anything  other  than  the  meaning. 
We  are  always  concerned  with  the  thing  meant  and  take 
that  for  granted  with  no  attempt  to  determine  how  the 
object  is  represented  in  consciousness  or  how  what  is  in 
consciousness  can  represent  the  thing.  At  present  two 
main  theories  are  in  the  field.  The  one,  suggested  by 
Kiilpe  and  the  so-called  Wiirzburg  school  and  by  Wood- 
worth,  asserts  that  all  meaning  comes  immediately  and 
cannot  be  explained,  that  it  is  an  immediate  fact  of  con- 
sciousness, perhaps  the  most  important  fact  of  con- 
sciousness, and  that  is  all  that  can  be  said  of  it.  They 
would  assert  that  in  addition  to  the  images  and  sensations 
in  consciousness,  there  is  another  sort  of  mental  function, 


REASONING  389 

the  meaning,  and  that  all  reasoning  and  practically  all 
other  mental  operations  are  carried  out  in  terms  of  it. 
The  meaning  needs  no  images  even  to  carry  the  refer- 
ence. When  one  thinks,  one  rises  to  a  new  realm  of  pure 
thought  that  is  not  definitely  related  to  the  ordinary 
state  of  consciousness.  The  second  theory  finds  the 
explanation  of  meaning  in  the  associates  that  have  been 
formed  with  the  image  in  question  and  which,  through 
their  arousal,  or  partial  arousal,  give  rise  to  the  meaning. 
Theories  of  Meaning.  —  In  discussing  the  theories,  the 
first  thing  to  be  kept  in  mind  is  that  the  assumption  of 
meaning  as  fundamental  is  not  a  proof.  We  must  take 
very  much  the  same  attitude  towards  it  as  towards  the 
nativistic  theory  of  space.  It  is  something  to  be  ac- 
cepted if  no  other  explanation  can  be  found.  Of  itself 
it  is  no  explanation,  merely  a  denial  that  any  of  the 
earlier  suggestions  hold.  The  imageless  characteristic 
of  meaning  must  be  kept  in  mind  as  we  run  through  the 
results  of  earlier  discussions  to  find  analogies  for  meaning. 
In  this,  as  in  the  representative  character,  the  simpler 
processes  offer  many  points  of  similarity.  Meaning 
offers  the  same  problem  as  the  local  sign  in  space  per- 
ception. There  we  found  that  the  touch  was  always 
referred  outward  to  the  skin,  meant  a  point  on  the  skin, 
but  no  one  could  say  from  examination  of  the  mental 
state  what  it  was  that  made  it  mean  that  point.  This 
is  one  of  the  simplest  cases  of  imageless  reference,  but 
few  people  have  been  content  to  stop  with  recognition 
of  that  fact.  As  we  have  seen,  many  attempts  have 
been  made  to  discover  what  might  be  involved  in  that 
reference.     This  fact  of  imageless  reference  of  percep- 


390  FUNDAMENTALS    OF   PSYCHOLOGY 

tions  outward  characterizes  all  space  perception.  The 
appreciation  of  the  distance  of  an  object  by  the  eyes  or 
ears  is  a  similar  instance  of  reference  that  can  be  given 
no  explanation  from  immediate  observation.  One  is 
aware  that  the  object  is  at  a  certain  distance  but  has  no 
direct  means  of  determining  how  one  knows.  Here  ex- 
perimental analysis  has  been  more  successful  than  in  the 
localization  of  stimulations  on  the  surface  of  the  body. 
As  we  have  seen,  the  reference  outward  depends  upon 
the  presence  of  strains  from  eye  muscles,  intrinsic  and 
extrinsic,  upon  double  images,  in  themselves  not  noticed, 
which  have  become  associated  with  different  distances. 
It  is  characteristic  of  this  reference  also  that  the  occasion 
for  thinking  of  a  particular  distance  is  never  noticed ;  one 
thinks  of  the  distance  itself  without  any  known  inter- 
mediary. The  objects  are  thought  of  as  at  a  distance 
from  us,  and  we  think  of  nothing  but  the  objects  as  out- 
side ;  we  have  no  notion  that  the  impression  is  inside 
and  projected  outward  on  the  basis  of  some  sensory  con- 
tent, plus  associations. 

The  same  general  rule  holds  of  all  perceptions.  One  is 
not  aware  of  the  letters  or  the  words  in  reading ;  the  mean- 
ing alone  comes  to  consciousness.  The  sensory  content 
at  the  basis  of  the  appreciation  of  the  meaning  is  not 
noticed ;  it  is  shown  to  have  an  existence  only  by  experi- 
ments. Even  in  the  optical  illusions  the  same  process 
can  be  shown  to  exist  and  is  more  striking,  as  the  mean- 
ing that  is  supplied  is  out  of  harmony  with  the  facts,  and 
thus  can  in  no  way  be  referred  to  an  immediate  apprecia- 
tion of  external  reality.  One  looks  at  the  Miiller-Lyer 
figure,  e.g.,  and  sees  nothing  more  than  that  one  line  is 


REASONING  39 1 

longer  than  another.  The  intermediate  steps  are  not  ap>- 
preciated,  and  again  can  be  inferred  only  from  various  tests 
and  analogies.  In  each  of  the  forms  of  perception  that 
have  been  discussed,  —  and  many  others  could  be  men- 
tioned, —  we  find  a  typical  case  of  what  has  been  called 
imageless  reference.  The  explanation  of  all  is  found  in 
the  presence  of  certain  sensory  elements  which  have  had 
associations  with  other  experiences  that  are  altogether 
different,  and  in  each  case  the  notion  that  has  been 
associated  with  the  experience  is  what  comes  to  con- 
sciousness. The  images  that  represent  it  in  conscious- 
ness are  not  themselves  noticed,  are  unconscious,  if  one 
may  indulge  in  paradoxes. 

Meaning  Related  to  Recognition.  —  Another  analogy 
with  meaning  is  offered  by  recognition.  A  name  presents 
itself  as  one  is  reading  and  at  once  it  is  noticed  that  it 
seems  familiar,  one  is  prepared  to  accept  it.  This  offers 
one  of  the  best  instances  of  mental  state  or  process  that 
has  full  and  immediate  meaning.  If  one  takes  an  in- 
stance of  delayed  or  obstructed  recognition,  it  has  been 
shown  in  the  last  chapter  that  one  places  the  name  by  the 
gradual  addition  of  associates.  If  the  name  is  of  an 
author,  recognition  comes  when  some  of  his  works  are 
recalled  in  connection  with  him ;  in  cases  of  personal 
famiharity,  the  face  or  a  picture  of  the  face  may  be  added 
before  recognition  is  complete.  Recognition  is  practi- 
cally always  through  associations.  Recognition  contains 
all  of  the  elements  of  meaning.  If  the  recognition  is  not 
particular  but  the  object  is  a  new  member  of  a  familiar 
class,  to  cognize,  to  have  the  object  take  on  meaning,  is 
practically  identical  with  a  reference  to  that  general 


392  FUNDAMENTALS   OF  PSYCHOLOGY 

class.     If  recognition  consists  in  the  addition  of  asso- 
ciates which  may  or  may  not  be  fully  conscious,  it  is 
certainly  possible  and  altogether  probable  that  meaning 
is  a  generalized  form  of  recognition,  and  should  also  be 
due  to  the  addition  of  associates.     As   the  associates 
in  recognition  are  not  conscious  as  discrete  processes  in 
most  cases,  so  in  meaning  the  associates  are  not  ordi- 
narily fully  developed  and  may  be  entirely  unconscious. 
The  relation  between  recognition  and  meaningful  mate- 
rial in  memory  has  already  been  indicated  in  the  last 
chapter.     Recognition  and  meaning  follow  approximately 
the  same  laws.     One  remembers  material  that  can  be 
recognized  in  about  the  same  proportion  as  memory  that 
has  meaning.     Recall  and  recognition  of  nonsense  ma- 
terial require  approximately  the   same   time.     Only  in 
material  that  has  its  associates  already  fully  fixed  is  it 
possible  to  recognize  more  easily  than  to  recall.     Mean- 
ingful material  in  memory  is  such  as  may  be  referred  to 
more  general  heads,  to  more  general  notions,  or  to  other 
things  that  are  in  themselves  familiar.     If  we  bring  to- 
gether the  relations  between  meaning  and  the  other  forms 
of  reference  that  we  have  dealt  with  in  the  more  concrete 
processes,  we  find  that,  as  in  perception  and  recognition, 
the  thing  meant  is  usually  all  that  is  in  consciousness  at 
any  time,  that  neither  the  sensory  elements  which  make 
the  reference  nor  the  associates  that  may  be  said  to  con- 
stitute or  at  least  to  furnish  a  basis  for  it  are  definitely 
in  mind  with  it.     On  the  other  hand,  in  most  cases  it 
can  be  shown  indirectly  that  associates  really  give  rise 
to  the  meaning,  and  in  others  it  seems  probable  from  anal- 
ogy that  associates  in  the  physiological  sense  play  the 


REASONING  393 

important  part  in  gi\ing  meaning,  in  making  the  refer- 
ence. This  theory  assumes  that  there  is  a  consciousness 
of  meaning  that  comes  with  the  opening  of  association 
paths,  even  when  the  associates  do  not  fully  come  to  Ught. 
The  same  assumption  is  necessary  if  we  are  to  hold  that 
recognition  may  come  as  a  result  of  associates  when  no 
definite  associates  are  apparent  and  if  we  are  to  explain 
reference  of  a  touch  to  a  certain  portion  of  the  skin  or  of 
a  \isual  percept  to  a  definite  distance,  when  one  is  not  at 
all  aware  of  the  sensory  elements  that  lead  to,  nor  of  the 
associates  that  constitute,  the  reference. 

We  may  grant,  then,  wath  the  exponents  of  the  pure 
thought  theory,  that,  as  a  conscious  content,  meaning 
differs  from  what  are  called  the  static  elements,  but  we 
would  insist,  on  the  other  hand,  that  it  is  an  outgrowth 
or  accompaniment  of  the  opening  of  cerebral  paths,  on 
the  same  level  as  those  that  lead  to  recall.  Secondly, 
we  may  assume  with  them  that  the  quaUty,  state,  or 
function  is  not  one  that  appears  seldom  and  only  in  con- 
nection with  reasoning,  but  rather  it  is  fundamental  to 
all  concrete  mental  processes,  low^  as  well  as  high.  The 
states  that  have  not  meaning  must  be  regarded  as  the 
exceptions  to  be  explained  rather  than  the  reverse.  One 
should  add  that  in  all  states  from  percepts  to  abstract 
thought,  the  meaning  alone  may  dominate  consciousness 
and  the  element  that  might  be  said  to  carry  the  meaning 
may  have  no  existence  or  be  lost  in  its  meaning,  as  the 
local  sign  is  lost  in  the  reference  to  a  point  on  the  skin. 
The  only  exception  we  take  to  the  other  school  is  that 
they  regard  meaning  as  immediately  given,  while  we  be- 
lieve it  is  derived.     The  meaning,  then,  may  be  defined 


394  FUNDAMENTALS   OF   PSYCHOLOGY 

as  the  fact  of  reference  from  some  state  or  process  out- 
ward, a  fact  of  reference  that  may  be  an  unanalyzable   ^ 
state  of  consciousness,  but  which  probably  depends  upon., 
the  presence  of  partially  opened  association  paths. 

The  Concept  as  Representative.  —  Equally  important 
for  reasoning  and  recognized  much  earlier  than  the  mean- 
ing is  the  concept.     The  concept  is  usually  defined  as 
an  abstract  idea  that  contains  elements  of  many  particu- 
lars.    For  the  logician,  'man'  in  the  abstract  means  all  • 
men,  either  as  representative  of  the  class,  or  as  contain-  * 
ing  all  the  quaHties  of  humanity  as  a  whole.     Water  as  • 
a  concept  might  be  represented  by  a  chemical  formula,  • 
by  its  physical  qualities,  or  it  might  be  regarded  as  a  type  ' 
of  all  the  different  particular  kinds  of  water.     There  is. 
always  in  the  concept  something  of  the  representative, 
and  something,  too,  of  the  organized,  harmonized,  and  • 
corrected  experience.     In  so  far  as  the  concept  is  repre-  - 
sentative,  it  is  closely  related  to  the  meaning,  it  may  be . 
regarded  as  the  mental  process  that  carries  the  meaning, 
and  becomes  a  concept  because  of  its  associates,  —  be- 
cause of  the  concrete  single  and  simple  experiences  that  > 
it  represents.     Thus,  I  may  think  the  word  '  man  '  and" 
intend  it  to  stand  for  all  men  in  a  certain  relation.     Be-  . 
cause  of  its  meanings,  its  associates,  the  word  does  duty  . 
for  all  of  the  particulars  ;  it  becomes  unnecessary  to  think 
of  each  separately  and  in  detail.     Regarded  from  this 
standpoint,  the  concept  as  a  mental  state  may  have  any 
form.     It  is  very  frequently  a  word,  sometimes  it  is  a 
single   object   that   stands  for  many   others.     Thus  a 
model  deposited  in  the  patent  ofhce  represents  legally 
all  machines  that  may  be  constructed  on  a  given  plan. 


REASONING  395 

no  matter  of  what  size  or  of  what  materials  they  may  be 
made.  A  drawing  of  a  geometrical  figure  may  be  repre- 
sentative of  all  figures  of  any  size  and  of  many  shapes. 
The  various  single  objects  that  it  represents  may  be  said 
to  be  the  meaning  of  the  figure ;  they  are  the  associates 
that  it  does  or  may  call  out,  and  what  is  affirmed  of  it 
holds  of  each  of  the  others  also.  It  is  possible  to  make 
assertions  in  this  way  of  the  concept  because  each  of  the 
elements  that  it  represents,  each  of  the  partially  awa- 
kened associates,  would  prevent  any  assertion  that  would 
not  hold  as  well  of  each  of  the  particulars.  It  is  in  terms 
of  concepts  of  this  sort  that  one  may  reason  in  abstract 
terms  ;  although  the  concept  itseK  as  a  mental  content  is 
particular,  it  represents  an  abstraction  or  a  number  of 
concrete  objects. 

Concept  as  Type.  — •  In  another  sense,  however,  the 
concept  may  be  the  thing  that  is  meant.  It  may  be  what 
is  referred  to  by  the  mental  content.  This  second  sort 
of  concept  is  what  is  represented  by  the  concept  in  the 
sense  used  above.  In  this  sense  all  knowledge  is  made 
up  of  concepts,  and  these  are  related  to  the  particulars 
as  the  fuUy  unified  to  the  rough  materials.  One  may 
picture  the  system  of  knowledge  as  made  up  of  various 
elements  that  have  been  fitted  together  to  constitute  a 
consistent  whole.  These  elements  are  for  the  most  part 
not  given  immediately  in  sensation,  but  are  the  results  of 
various  refinements,  of  various  ways  of  working  over 
the  raw  materials,  until  some  order  is  brought  into  the 
originally  inchoate  mass.  We  have  seen  the  process  at 
work  even  in  perception.  As  was  pointed  out  there 
on  several  occasions,  what  is  perceived  is  not  merely  a 


396  FUNDAMENTALS   OF   PSYCHOLOGY 

mass  of  sensations,  nor  is  it  a  single  sensation  that  sug- 
gests some  other  single  sensation  or  group  of  sensations ; 
rather  is  it  a  type,  an  organized  product  of  many  experi- 
ences which  have  finally  given  rise  to  a  construct  con- 
sistent with  all  of  our  different  related  experiences.  This 
it  is  that  is  thought  when  a  single  stimulus  presents 
itself.  Thus,  to  repeat  our  simple  instance,  we  see  the 
top  of  a  table  as  square,  not  because  it  is  square  on  the 
retina,  nor  because  we  have  seen  it  more  frequently  under 
conditions  that  make  it  appear  square  than  when  dis- 
torted by  perspective,  —  probably  it  never  has  been  seen 
undistorted,  —  but  because  all  that  we  know  about  the 
table  top  harmonizes  with  the  assumption  that  it  is  square. 
When  tested  or  measured  it  proves  to  be  square ;  a  simi- 
lar surface  must  be  made  with  right  angles,  it  fits  into 
square  corners.  It  is  believed  to  be  square  because  that 
assumption  fits  in  with  all  of  our  other  experiences. 

Development  of  Concepts.  —  It  is  by  this  method  that 
most  of  the  notions  of  external  objects  develop.  Posi- 
tion is  a  notion  that  cannot  be  referred  to  any  single 
experience.  Depth  also  cannot  be  said  to  be  merely  the 
sensation  of  the  motion  necessary  to  reach  the  object, 
but  is  rather  a  concept  or  type  developed  through  many 
tests  and  accepted  because  it  harmonizes  or  orders  many 
different  experiences.  Space  in  general  is  a  similar  type. 
If  we  turn  from  perception  to  less  objective  things,  the 
same  principle  may  be  applied.  The  development  of 
the  number  concept  can  be  followed  among  the  different 
primitive  nations.  In  northern  Borneo,  the  natives 
still  have  no  developed  notion  of  number  apart  from  ob- 
jects.    When  counting  they  use  the  fingers  and  toes, 


REASONING  397 

and  when  the  number  rises  above  twenty,  another  man  is 
called  and  the  objects  are  checked  against  his  fingers  and 
toes.  The  remnants  of  this  counting  can  easily  be  traced 
in  the  decimal  system  and  in  the  score.  In  this  instance 
the  concept  carries  with  it  more  of  the  original  sensory 
material  from  which  it  develops  than  do  space  and  posi- 
tion, but  in  the  course  of  time  the  separation  from  the 
concrete  is  complete,  and  now  number  carries  with  it 
practically  no  impKcation  of  fingers  and  toes  except  for 
the  use  of  a  few  words,  such  as  digits. 

Elnowledge  a  System  of  Concepts.  —  Leaving  aside 
for  the  moment  the  question  of  how  the  concepts  develop, 
it  is  e\ddent  that  organized  knowledge  consists  in  its 
entirety  of  a  system  of  concepts.  When  anything  can 
be  referred  to  a  concept,  we  place  it,  we  can  use  it,  we 
understand.  On  the  other  hand,  when  it  is  possible  to 
develop  a  notion  or  concept  that  will  organize  a  group  of 
facts,  we  accept  the  concept  as  true  and  use  it  until  some 
new  facts  appear  that  are  out  of  harmony  with  it,  when 
that  concept  is  given  up  and  another  substituted  for  it. 
Just  as  in  the  perception  of  space,  the  concept  or  t>^e  is 
assumed  to  be  real  and  all  else  is  adjusted  to  it,  so  in 
science  or  philosophy  or  in  everyday  life  the  concepts 
are  accepted  as  the  reals,  other  experiences  are  merely 
appearance.  The  systems  of  concepts  are  by  no  means 
consistent  with  each  other,  but  must  be  consistent  within 
themselves.  Thus,  if  one  consider  the  experience  of  per- 
cei\ing  the  table  from  the  standpoint  of  the  concepts  of 
the  different  sciences,  we  would  be  told,  on  the  one  hand, 
that  it  was  nothing  but  a  mass  of  atoms  of  hydrogen  and 
carbon  and  oxygen  in  different  arrangements  with  a  few 


398  FUNDAMENTALS   OF   PSYCHOLOGY 

odd  elements  thrown  in ;  that  its  pecuKar  character  de- 
pended upon  the  way  the  atoms  were  grouped  in  the 
molecules.  For  the  chemist  it  is  this  and  nothing  more. 
For  the  physicist  the  picture  changes.  Atoms  go  into 
the  background  and  forces  come  to  the  front.  Attrac- 
tion for  the  earth  keeps  it  in  place  and  gives  it  weight. 
It  is  seen  by  the  vibrations  in  the  ether  that  it  reflects, 
and  its  color  is  determined  by  the  rays  that  it  absorbs 
and  reflects.  If  one  happens  to  be  talking  to  a  physicist 
of  the  latest  school,  electricity  replaces  ether  and  its 
vibrations.  In  any  case,  explanation  is  in  terms  of  a 
system  of  concepts,  however  the  concepts  may  differ. 
The  physiologist  finds  his  explanation  of  the  experience 
in  the  nervous  structure  of  the  eye,  in  photo-chemical 
processes  in  the  rods  and  cones,  in  the  excitations  and 
responses  of  the  neurones.  For  the  psychologist,  again, 
we  have  a  group  of  sensations  of  strain,  of  Hght  and 
shade,  of  images.  These  are  the  types  or  concepts  to 
which  experience  is  referred  as  the  psychologist  attempts 
to  understand  it.  In  short,  our  simple  experience  has  been 
dissolved  in  a  great  many  different  ways,  no  one  of  which 
leaves  anything  of  the  original  experience,  and  yet  with- 
out this  dissolution  into  concepts,  it  could  not  be  under- 
stood. 

Without  the  concepts  all  would  be  confusion.  This  is 
clear  from  a  study  of  the  early  languages  and  the  lower 
forms  of  human  thought.  It  is  asserted  that  among  the 
lower  south  African  tribes  there  is  no  notion  of  direc- 
tion in  the  absolute  sense.  The  individual  gropes  his 
way  from  place  to  place  by  memory  of  each  landmark 
along  the  way,  and  has  no  idea  in  which  direction  he  is 


REASONING  399 

going.  He  cannot  keep  his  bearing  even  with  reference 
to  the  rising  or  the  setting  sun.  How  confused  the 
notion  of  the  world  must  be  can  easily  be  appreciated. 
Similarly,  where  numbers  are  restricted  to  a  score,  where 
length  can  be  measured  only  in  paces,  or  in  days'  journeys, 
and  other  concepts  are  equally  faulty  or  altogether  lack- 
ing, all  thought  must  be  decidedly  vague  and  uncertain. 
Even  the  use  of  purely  personal  concepts  of  force,  as  in  the 
explanation  of  the  winds  and  other  natural  phenomena 
by  spirits,  and  the  general  anthropomorphic  explanation 
of  events  and  causes,  means  that  httle  progress  can  be 
made  in  the  accurate  understanding  or  use  of  natural 
forces.  Adequacy  of  the  concepts  means  adequacy  of 
understanding,  and  that  in  turn  means  successful  action 
and  appHcation  of  means  to  ends.  What  experience 
would  be  Kke  without  concepts  one  cannot  appreciate. 
It  would  be  of  course  a  hopeless  confusion,  Hke  waking 
from  a  bad  dream  into  an  entirely  new  environment. 
Nothing  would  be  clear,  nothing  would  be  definite.  For 
all  intents  and  purposes,  without  concepts  there  would 
be  no  consciousness.  Adequate  concepts  go  hand  in 
hand  with  possibility  of  adequate  thought. 

The  problem  of  the  origin  of  concepts  in  this  sense  of 
the  word  has  been  one  of  the  persistent  problems  of  phi- 
losophy. We  find  the  general  theories  divide  themselves 
like  the  theories  of  space  into  those  which  assume  con- 
cepts and  regard  them  as  determining  the  course  of  de- 
velopment of  knowledge,  and  those  which  would  develop 
the  concepts  themselves  from  and  through  experience. 
Plato,  for  example,  has  in  his  ideas  a  system  of  concepts 
that  are  innate,  the  representatives  in  man  of  the  eternal 


400  FUNDAMENTALS   OF  PSYCHOLOGY 

verities,  through  which  all  experience  obtains  what  truth 
it  may  have.  On  the  other  hand,  we  have  more  empiri- 
cal theories  that  would  derive  them  from  the  experience 
of  the  individual,  and  in  the  case  of  the  more  fully  devel- 
oped concepts,  as  worked  over  and  tested  by  the  race  on 
the  basis  of  individual  suggestions.  This  is  in  the  large 
the  suggestion  that  was  made  with  reference  to  the  types 
in  perception.  They  may  be  in  part  or  at  times  derived 
by  the  accumulation  of  particular  experiences  that  have 
been  consolidated  or  modified  by  use.  In  large  part  and 
in  many  cases,  however,  they  seem  to  result  from  hitting 
by  chance  upon  some  construction  that  harmonizes  with 
the  experiences.  When  a  construction  is  found  that 
meets  this  test,  it  is  accepted.  Certain  it  is  that  con- 
cepts are  modified  with  the  passage  of  time  and  the 
growth  of  knowledge,  and  it  is  just  as  certain  that  a 
concept  is  seldom  the  direct  product  of  the  action  of  the 
senses.  In  the  formation  of  laws,  experimental  science 
shows  a  tendency  to  consolidate  particular  observations 
into  generalizations  and  also  a  tendency  for  trial  and  error 
to  play  a  part  in  the  formation  of  concepts.  For  our 
purposes  it  is  more  important  to  insist  that  our  knowl- 
edge, as  used  in  thought  and  developed  through  per- 
ception, becomes  largely  a  system  of  concepts,  of  types, 
and  that  these  serve  to  explain  the  concrete  and  in  many 
cases  in  themselves  to  constitute  the  concrete.  Without 
them  knowledge  would  be  no  knowledge  but  a  mere  mass 
of  confusion. 

Concept  as  Representative  Idea  and  as  T5rpe.  — 
Two  forms  of  the  concept  may  then  be  distinguished. 
The  first  is  a  definite  mental  state  that  means  a  number 


REASONING  401 

of  particulars  or  a  number  of  general  qualities  of  any 
sort.  This  takes  the  form  of  a  word,  a  t>'pical  group  of 
sensations,  or  may  reduce  to  nothing  or  very  nearly 
nothing  but  the  meaning,  the  reference  itself.  The 
second  form  is  an  organized  idea,  a  type  that  has  been 
proved  by  tests  to  satisfy  many  experiences,  and  in  con- 
sequence is  accepted  as  real.  It  is  this  concept  that  is 
usually  meant.  It  is  what  we  accept  as  the  external  ob- 
ject of  common  sense,  it  is  the  fundamental  structure  or 
force  or  principle  of  explanation  in  natural  science,  or 
in  psycholog}\  Such  concepts  are  our  sensations,  our 
associations  and  percepts,  —  in  fact,  all  of  the  notions 
that  we  have  been  developing  in  the  attempt  to  explain 
mental  life.  In  many  cases  these  types,  too,  are  not 
absolutely  clearly  pictured  but  are  represented  in  con- 
sciousness in  some  schematic  fashion.  At  other  times, 
as  in  perception,  the  t>pes  constitute  the  clearest  and 
most  definite  structures  of  consciousness.  They  are 
consciousness,  and  all  else  is  subordinated  to  them.  In 
every  case  they  are  all  that  we  are  really  conscious  of 
at  the  moment,  whether  they  be  meant  merely  or  whether 
they  be  actually  reproduced  in  all  their  clearness. 

The  Stages  of  Active  Reasoning.  —  At  each  point  in 
active  reasoning,  use  is  made  both  of  meaning  and  of 
the  concept.  Most  of  reasoning  consists  in  bringing  order 
into  experience  and  in  justif}ing  suggestions  for  new 
advances.  In  both,  reference  to  the  established  system 
of  knowledge,  to  concepts  and  generally  accepted  laws, 
plays  a  prominent  part.  Practically  all  reasoning  opera- 
tions deal  with  real  things  or  their  symbols,  involve 
meaning  only.     The  active  processes  in  reasoning  may 


402  FUNDAMENTALS   OF  PSYCHOLOGY 

be  divided  for  convenience  into  four.  These  are  the  in- 
centive to  reason  which  is  usually  forced  upon  us  by  some 
difficulty,  some  opposition  to  progress  either  in  action 
or  in  thought,  or  something  which  makes  a  continued 
inaction  undesirable.  The  second  '  is  to  analyze  the 
difficulty,  to  understand  it.  This  constitutes  judgment. 
After  the  difficulty  is  understood,  means  must  be  discov- 
ered for  removing  it,  and  this  we  know  a^  inference. 
Finally,  the  conclusion  m^st  be  tested,  must  be  shown  to 
be  correct,  and  this  constitutes  proof.  These  states  must 
be  considered  one  by  one.  ^  (;Reasoning  as  a  whole  must 
have  a  positive  stimulus.  The  problem  is  always  forced 
upon  the  individual  by  some  inadequacy  of  old  habits  or 
of  old  thoughts,  by  something  that  goes  wrong  in  the 
ordinary  routine.  Where  habit  and  routine  suffice,  one 
never  reasons.  Necessity  is  the  mother  of  all  thought, 
as  of  all  invention.  The  problem  usually  presents  itself 
by  the  man's  being  thwarted  in  his  mental  or  physical 
progress.  On  the  mental  side  some  fact  presents  itself 
that  will  not  fit  into  the  theories  already  developed.  The 
number  of  species  of  beetles  challenged  Darwin  to  discover 
a  reason,  the  ffight  of  birds  and  insects  challenged  Langley 
and  Wright  to  find  some  mechanical  means  of  imitating 
them.  Each  suggestion  that  ideas  may  be  reaHzed  starts 
the  discoverer  on  a  quest  for  the  means.  Granted  the 
problem,  the  next  stage  is  an  analysis  of  the  problem  into 
its  elements  or  conditions  to  obtain  a  better  understand- 
ing of  what  is  to  be  done. 

Judgment.  —  This  process  of  ^nalysi^  consists  of  a 
reference  of  the  parts  of  the  problem  to  its  peculiar  con- 
cept or  class.     The  process  of  reference  -to  a  type  is 


REASONING  403 

known  as  the  judgment.  In  the  solution  of  any  mechani- 
cal problem,  the  building  of  a  bridge,  e.g.,  it  is  necessary 
to  reduce  the  various  strains  to  their  components,  to  meas- 
ure the  intensity  of  each,  before  means  can  be  found  for 
resisting  them.  In  designing  a  building,  the  engineer 
goes  beyond  the  ordinary  rule  of  thumb,  determines  how 
much  pressure  the  building  wall  exert  downward,  how 
much  will  be  expended  in  lateral  thrusts,  what  the  wind 
pressure  is  likely  to  be  at  a  maximum,  and  only  when 
these  various  components  of  the  problem  have  been  de- 
termined is  he  ready  to  decide  what  material  must  be  used 
and  how  the  structural  elements  may  be  distributed. 
The  process  of  analysis  is  essential  at  every  step  in  ad- 
vance of  action.  It  consists  in  referring  the  new  to  old 
and  familiar  experiences  so  far  as  the  new  offers  points  of 
similarity  with  the  old.  This  is  the  first  point  at  which 
the  background  of  older  experience  aids  in  the  new  con- 
struction, in  progress  of  any  sort.  Only  in  so  far  as  the 
problem  can  be  reduced  to  its  parts  and  the  parts  referred 
to  established  concepts  can  it  be  said  to  be  understood, 
and  only  then  is  it  possible  to  go  ahead  safely.  To  act 
before  the  situation  is  understood  is  to  act  in  the  dark  and 
ineffectively. 

The  process  of  judging  consists  of  the  reference  of  a  new 
experience  or  an  entering  sensation  to  an  old  concept. 
In  one  sense  it  is  simply  the  perception  process  over  again. 
A  stimulus  presents  itself  and,  before  it  is  really  conscious, . 
it  is  referred  to  some  old  type  ;  it  is  given  a  meaning,  and 
thereby  becomes  fully  conscious.  The  process  called 
judgment  by  the  formal  logician  is  approximately  the 
same,  although  more  explicit  and  definitely  represented 


404  FUNDAMENTALS    OF   PSYCHOLOGY 

in  words.  Thus  '  man  is  mortal '  is  a  judgment ;  man 
is  the  subject,  mortal  is  the  predicate.  The  subject  repre- 
sents the  presented,  the  thing  given  to  be  understood, 
and  the  predicate  the  concept  by  which  it  is  explained. 
The  process  of  judging  brings  the  new  under  some  head 
or  category  already  established. 

Judgments  of  Relation  and  Evaluation.  —  In  addition 
to  this  use  of  the  term  judgment  to  designate  the  refer- 
ence of  the  unknown  to  some  definite  concept,  it  is  used 
also  to  indicate  comparison  and  evaluation,  uses  more 
closely  related  to  the  popular.  One  is  said  to  judge 
when  one  compares  two  lines  and  also  when  one  estimates 
the  value  of  anything,  assigns  the  money  value  to  a  horse 
or  other  article  of  merchandise,  or  estimates  the  guilt 
of  the  prisoner  at  the  bar.  In  each  case  there  is  approxi- 
mately the  same  process.  One  has  a  scale  of  values  that 
has  been  developed  in  the  course  of  many  experiences. 
The  present  article  is  given  its  place  in  the  Hst  on  the  basis 
of  various  similarities  to  things  judged  before,  some  ex- 
plicit, some  implicit  and  indefinite.  A  similar  process 
is  present  in  judicial  decisions.  A  particular  crime  is 
referred  to  the  general  scale  and  the  punishment  affixed 
in  accordance  with  the  scale.  Comparisons  are  also 
references  to  types,  but  to  typical  relations  not  to  typical 
things.  Relations  are  as  much  concepts  as  are  space  or 
time.  Greater  and  less  are  typical  relations  developed 
to  make  it  possible  to  understand  certain  phases  of  ex- 
perience. To  measure  it  was  necessary  to  develop  the 
concepts  of  relation  in  space  and  time  and  energy,  and 
measurement  is  the  foundation  of  civilized  life.  When  one 
asserts  that  a  line  is  longer  than  another,  one  merely  looks 


REASONING  405 

from  one  to  the  other  in  immediate  succession,  and  the  con- 
cept greater  or  less  suggests  itseh,  the  pair  is  referred  to 
one  class  or  the  other  immediately.  The  process  is  just 
like  the  recognition  of  a  new  object  or  any  similar  classi- 
fication. The  judgment  in  general  is  a  reference  of  a  new 
thing  or  situation  to  a  famiUar  head,  the  reference  of  a 
particular  or  unkno\vn  to  a  general  t\^e,  a  reference  that 
prepares  one  to  treat  it  adequately.  In  our  particular 
practical  case,  it  is  a  process  of  analyzing  the  elements  of 
the  problem  in  preparation  for  its  solution. 

Inference.  — -  Granted  that  the  problem  has  been  stated 
and  understood,  the  next  process  is  to  discover  a  solution. 
This  process  roughly  corresponds  to  the  inference  of  the 
formal  logician.  The  only  difference  Hes  in  the  fact  that 
formal  logic  is  inclined  to  combine  the  real  discovery  of 
the  solution  with  the  proof  that  it  is  the  solution.  Find- 
ing the  solution,  inference  in  our  sense,  consists  in  a  pro- 
cess or  series  of  processes^  of  association.  If,  when  the 
judgment  is  complete,  the  new  situation  can  be  reduced 
to  famihar  elements,  the  solution  is  practically  com- 
pleted ;  the  older  solutions  may  suffice  or  may  be  com- 
bined in  the  attainment  of  the  new  desired  end.  In  these 
cases  association  under  the  suitable  more  general  controls 
may  be  all  that  is  necessary.  In  many  other  instances 
the  process  cannot  be  reduced  to  laws,  although  probably 
each  suggestion  is  controlled  by  definite  laws  of  associa- 
tion. One  can  be  sure  only  that  there  will  be  many 
attempts  of  different  sorts  before  the  solution  is  finally 
reached.  Inference  has  more  points  of  resemblance  to 
an  animal  struggHng  to  get  out  of  a  box  or  to  the  man 
with  a  new  puzzle  than  to  the  ordinary  notion  of  the  ac- 


4o6  FUNDAMENTALS    OF   PSYCHOLOGY 

tion  of  a  calculating  human  being.  In  these  cases  the 
process  is  one  of  repeatedly  trying,  with  a  readiness  to 
reject  all  but  the  right  solution. 

Inference  a  Process  of  Trial  and  Error.  —  When  one  is 
trying  to  solve  a  puzzle,  first  one  movement  is  made 
and  then  another,  until  finally  by  chance  success  is  at- 
tained. In  thinking  out  the  solution  for  a  problem  very 
much  the  same  process  is  used  except  that  the  trials  are 
only  in  thought.  One  thinks  of  some  way  of  changing 
the  thing  or  the  situation,  and  when  one  believes  that 
this  will  not  work  when  fully  developed,  tries  another. 
If  that  is  rejected,  then  a  third  is  presented ;  the  process 
continues  until  one  is  hit  upon  that  promises  to  work. 
With  difficult  problems  the  process  of  trying  solutions 
and  rejecting  them  may  last  for  hours,  and  of  course  in 
important  inventions  the  trials  may  continue  for  years 
before  the  right  solution  is  hit  upon.  Frequently,  an 
approximation  to  the  solution  will  be  reached  and  then 
the  process  of  transforming  or  perfecting  will  go  on  by 
the  same  method  for  an  equally  long  time  before  what 
can  be  considered  a  complete  solution  will  be  hit  upon. 
In  the  case  of  actual  inventions  or  the  solution  of  actual 
problems,  the  final  satisfaction  may  come  ahnost  by  acci- 
dent, if  one  can  distinguish  between  accident  and  inten- 
tion in  such  an  operation.  Almost  the  only  direction 
that  can  be  given  for  the  attainment  of  the  end  is  to  keep 
trying.  Persistence  is  the  only  virtue,  the  rest  is  very 
largely  a  matter  of  chance.  There  are  certain  minds  in 
which  ideas  spring  readily,  that  seem  fertile  in  suggestions 
of  all  sorts ;  certain  others  that  practically  never  get 
away  from  the  commonplace,  from  the  prosaic  memories. 


REASONING  407 

Blessed  is  he  whose  psychophysical  disposition  is  of  the 
fonner  type.  If  he  happens  not  to  possess  this  touch 
of  genius,  nothing  can  be  done  but  substitute  persistence 
and  methodical  trial  for  the  quick  advances  of  the  chosen 
few.  No  rules  can  be  given  for  changing  the  unfertile 
brain  into  the  fertile  one,  nor  for  the  better  use  of  the 
fertile. 

In  the  unusualness  of  the  associations  and  connections 
that  are  made  lies  the  one  point  of  similarity  between  the 
abnormal  or  insane  brain  and  the  brain  of  genius.  )  Both 
are  constantly  calling  up  ideas  in  connections  that  would 
be  impossible  to  the  average  mind.  Tests  of  the  asso- 
ciations of  the  insane  show  that  their  range  of  associa- 
tions for  a  given  set  of  words  is  very  much  greater  than 
in  the  normal  group.  The  results  obtained  by  the  man 
of  genius  prove  the  same  departures  from  the  common- 
place, —  in  this  case  called  original.  The  difference  be- 
tween the  two  sorts  of  mental  fecundity  is  found  in  the 
nature  of  the  originality.  In  the  insane  there  is  little  con- 
trol, the  associates  are  not  at  all  restricted  by  the  nature  of 
the  environment,  or  by  any  appropriateness  to  the  situa- 
tion. In  the  effective  man  of  genius,  they  are  checked 
and  restrained  to  correspond  to  the  wider  demands  of 
the  moment.  The  second  still  more  important  difference 
is  to  be  found  in  the  repression  on  the  part  of  the  normal 
man  of  the  suggestions  that  are  not  suited  to  the  occasion, 
to  the  end  in  view.  The  speech  of  an  insane  man  may  be 
merely  a  '  word  salad,'  an  outpouring  of  words  in  any 
connection ;  in  the  normal  these  absurdities  are  inhibited, 
and  if  they  present  themselves  at  all,  only  those  are 
uttered   that  pass  the  censor.     Ability  to  distinguish 


408  FUNDAMENTALS    OF   PSYCHOLOGY 

between  the  appropriate  and  the  inappropriate  is  the  pri- 
mary mark  of  the  normal  as  opposed  to  the  abnormal. 
This  serves,  too,  to  emphasize  the  stages  of  the  inference. 
One  must  first  have  the  suggestion  that  is  to  constitute 
the  solution,  but  must  also  have  the  capacity  of  knowing 
when  the  right  solution  has  made  its  appearance.  Rea- 
sonable freedom  in  suggestion  is  desirable,  but  absolutely 
essential  is  the  capacity  to  appreciate  the  right  sugges- 
tion when  it  comes,  and  to  be  satisfied  with  no  less  than 
the  full  solution. 

Sometimes  the  right  suggestion  comes  by  chance,  some- 
tirnes  it  appears  when  thinking  of  something  else,  some- 
times one  is  merely  fumbling  with  the  object  that  one 
wants  to  improve  in  some  way  and  makes  the  proper 
change  without  any  preKminary  thought,  sometimes  it  is 
said  inventions  have  been  dreamed.  Jastrow  quotes  an 
instance  of  an  archaeologist  who  dreamed  the  reconstruc- 
tion of  the  results  of  certain  of  his  excavations  and  found 
that  they  were  satisfactory.  It  is  said  that  the  eccentric 
on  the  steam  engine  was  invented  by  the  boy  who  had 
been  set  to  open  and  close  the  valves  when  the  piston 
should  change  its  direction.  When  he  saw  some  boys 
he  wanted  to  play  with,  it  chanced  that  he  saw  a  place  to 
put  a  stick  where  it  would  do  the  work  he  was  doing,  so 
slipped  it  in  and  went  off  to  play.  Whether  the  anecdote 
be  true  or  not,  it  illustrates  how  inventions  may  be  made. 
It  makes  no  difference  how  the  suggestion  comes  provided 
it  is  recognized  as  appropriate  when  it  comes,  for  inference 
is  then  complete.  Obviously  it  is  quite  as  important  to 
make  proper  selection  from  among  the  suggestions,  as 
it  is  to  have  the  suggestion.     In  this  respect  reasoning 


REASONING  409 

is  like  memory.  The  associations  that  arise  in  the  at- 
tempt to  recall  correspond  to  the  suggestions  in  reasoning. 
Passing  upon  the  correctness  of  the  recall  found  in  recog- 
nition corresponds  to  acceptance  of  the  solution.  We 
shall  find  that  many  of  the  action  processes  have  a  simi- 
lar distinction,  that  many  operations  involve  a  process  of 
trial  and  error  in  the  productive  operation,  controlled  by 
some  means  of  testing  the  attainment  of  the  end. 

Belief  and  Proof.  —  It  is  particularly  essential^  then, 
that  we  understand  this  testing  or  censoring  process  in 
cormection  with  reasoning.  Two  phases  may  be  dis- 
tinguished. One,  behef,  is  implicit,  comes  immediately 
and  without  any  definite  consciousness  of  the  conditions 
that  he  behind  it;  the  other,  proof,  is  more  explicit, 
attempts  to  make  clear  why  the  thinker  believes,  and  why 
others  should  accept  the  inference.  Behef  gives  no 
warrant  for  itself ;  one  knows  only  that  one  does  be- 
Heve,  and  can  tell  why  only  from  a  study  of  the  condi- 
tions under  w^hich  belief  makes  its  appearance.  Neither 
the  feeling  of  belief  nor  the  conditions  that  compel  belief 
are  fully  conscious.  In  fact,  the  feeling  of  beHef  can  be  de- 
scribed only  in  negative  terms.  We  beHeve  all  that  is 
not  doubted,  —  the  persistent  unquestioned  presence  of 
any  idea  constitutes  belief.  Doubt,  on  the  other  hand, 
comes  with  alternations  in  the  interpretations,  is  due  to 
a  constant  change  from  one  to  another  of  the  ways  of 
looking  at  an  object.  The  cause  of  the  fluctuation  is  to  be 
found  in  the  changing  points  of  \^ew  from  which  the  fact 
is  considered,  —  in  the  different  complexes  of  experience 
that  serve  to  bring  up  first  one  interpretation,  then 
another.     Thus,  if  one  is  considering  a  general  problem, 


4IO  FUNDAMENTALS    OF    PSYCHOLOGY 

such  as  the  advantages  of  controlled  monopoly  as  op- 
posed to  unlimited  competition,  one  will  think  of  the 
advantages  of  large  production,  of  the  encouragement  to 
capital  from  certain  returns,  on  the  one  side,  and  will 
believe  in  monopoly ;  when  one  thinks  of  the  tendency  of 
human  nature  to  think  first  of  its  own  advantages  and  of 
the  growing  callousness  of  the  dictator  to  those  dependent 
upon  him,  permission  to  combine  seems  undesirable, 
belief  in  monopoly  is  refused.  The  checks  that  come 
from  state  control  will  remove  the  doubt  for  a  moment 
until  the  difficulties  in  exercising  impartial  control  pre- 
sent themselves,  when  the  old  state  of  doubt  reasserts 
itself.  Doubt  is  an  expression  of  the  conflict  in  various 
beliefs,  and  the  beliefs  in  turn  depend  upon  the  presence 
of  various  groups  of  experiences  which  make  for  the 
prominence  of  one  attitude  or  another  toward  the  asser- 
tion that  is  questioned. 

In  its  less  expHcit  forms  belief  seems  to  be  an  expres- 
sion of  the  harmony  of  a  particular  statement  with 
the  dominant  group  of  experiences.  This  may  be  seen 
to  advantage  in  the  changes  in  belief  as  dift'erent 
possibilities  are  considered.  When  one  is  caught  off 
one's  guard,  when  a  proposition  is  viewed  in  the  light 
of  a  limited  group  of  experiences,  one  will  believe  what 
will  not  be  believed  under  ordinary  circumstances. 
An  exaggeration  of  the  condition  is  seen  in  the  dream, 
where  we  may  assume  that  large  areas  of  the  cortex  are 
inactive  and  only  the  remaining  few  control  conscious- 
ness. Then  one  will  believe  many  constructions  that  are 
rejected  as  soon  as  one  wakes.  In  the  one  case  the  dream 
need   harmonize   only  with   the   partial   consciousness, 


REASONING  41I 

but  as  soon  as  one  wakes  it  is  necessary  that  it  har- 
monize with  all  portions.  This  it  fails  to  do  and  is  at 
once  seen  to  be  bizarre.  In  the  play  attitude,  or  in  the 
artistic  attitude  as  in  novel  reading,  one  may  voluntarily 
hold  part  of  consciousness  out  of  action  and  pass  upon 
the  game  or  the  work  of  art  in  the  hght  of  a  partial 
experience.  In  this  mood  the  result  is  accepted  as  true 
for  the  moment,  although  one  is  aware  that  it  will  not 
seem  true  as  absolute  fact.  In  general,  beHef  is  agree- 
ment between  the  construction  of  the  moment  and  the 
total  experience.  The  awareness  of  the  agreement  no 
more  implies  the  presence  in  mind  of  all  of  the  facts  that 
are  involved  in  passing  upon  the  experience  than  recogni- 
tion implies  the  presence  of  the  associates  that  give  the 
entering  impression  a  place  in  the  past,  or  the  meaning  of 
an  image  involves  the  full  presence  of  all  that  is  meant. 
Rather  the  thing  beheved  merel}^  holds  the  centre  of  the 
stage  without  wavering  or  opposition,  and  that,  with  pos- 
sibly some  shght  feeling,  constitutes  belief. 

Proof  a  Justification  of  Belief.  —  WTiile  beHef  is  suffi- 
cient justification  for  a  conclusion  on  the  part  of  the 
person  who  believes,  the  conclusion  may  not  appeal  so 
strongly  to  the  listener  or  to  others.  This  it  is  that  makes 
proof  necessary.  Since  justifying  the  conclusion  is  the 
one  part  of  the  reasoning  process  that  is  self-conscious, 
it  is  the  process  that  the  formal  logician  has  made  the 
most  of  and  which  he  is  incKned  to  consider  the  only  part 
of  the  reasoning  process.  Two  forms  of  proof  are  to  be 
distinguished,  the  deductive  and  the  inductive.  The 
typical  deductive  proof  is  through  the  syllogism,  and 
this  consists  in  essentials  of  referring  the  particular  con- 


412  FUNDAMENTALS    OF   PSYCHOLOGY 

elusion  to  some  generally  accepted  principle,  to  a  general 
law  that  is  typical  of  all  others.  Just  as  the  judgment 
consists  in  referring  some  particular  object  or  difficulty 
to  a  typical  difficulty  or  concept,  the  proof  consists  of 
finding  a  universal  statement  under  which  the  particular 
conclusion  that  has  been  obtained  may  be  brought  and 
thereby  made  to  seem  true.  First  it  should  be  said  that 
nothing  is  proved  that  is  not  questioned.  For  one's 
self  belief  suffices,  and  for  most  of  the  statements  of  every- 
day life  as  they  are  made  to  others  no  proof  is  necessary. 
Proof  is  given  only  when  one  hears  or  fears  objection 
from  one's  listeners,  or  when  one  desires  to  test  the  truth 
of  the  conclusion  for  one's  self  in  an  expHcit  form. 

Deductive  Proof.  —  The  proof,  as  given  by  the  formal 
logician,  is  in  the  syllogism,  but  the  syllogism  as  stated 
by  the  formal  logician  inverts  the  order  in  which  it  is  usu- 
ally appHed.  One  hits  upon  a  conclusion,  as  was  said 
above,  then  that  conclusion  is  proved  by  reference  to  an 
accepted  general  principle.  Thus,  to  use  a  favorite  in- 
stance of  formal  logic,  if  a  member  of  the  Areopagus 
has  thought  that  all  their  troubles  will  be  alleviated  some 
day  by  the  death  of  Socrates,  and  some  one  among  his 
hearers  questions,  he  justifies  his  conclusion  by  the  asser- 
tion that  Socrates  is  a  man  and  all  men  are  mortal. 
There  is,  of  course,  no  real  addition  to  the  knowledge  of 
either  in  the  statement ;  if  there  were,  it  would  not  be 
accepted  by  the  hearer,  and  so  would  carry  no  conviction. 
It  takes  its  value  from  the  fact  that  it  puts  in  a  brief  form 
the  common  knowledge  of  the  men  who  listen,  and  shows 
that  the  conclusion  reached  is  but  an  expression  of  that 
common  knowledge.    The  syllogism  is  usually  stated 


REASONING  413 

with  the  major  premise  or  general  statement  first,  and 
the  minor  premise  and  conclusion  following.  Thus,  our 
instance  would  run  in  its  t}'pical  form : 

All  men  are  mortal. 
Socrates  is  a  man ; 
Therefore  Socrates  is  mortal. 

Coupled  with  this  is  the  beHef  that  the  syllogism  is  it- 
self a  form  of  reasoning,  rather  than  a  form  of  proof. 
A  Httle  observation  of  the  actual  thinking  indicates  that 
one  does  not  in  practice  reach  the  conclusion  in  this 
way,  but  has  hit  upon  it  by  some  less  regular  process. 
The  syllogism  was  probably  regarded  as  the  form  of 
obtaining  conclusions  as  well  as  the  method  of  proving 
them  because  that  is  the  only  part  of  the  operation  that 
is  fully  conscious ;  and  as  reaching  the  conclusion  is 
most  important,  it  was  identified  mth  the  conscious 
operation.  The  suggestions  come  by  many  ways,  and 
are  not  considered  until  one  begins  to  question  whether 
they  are  to  be  accepted.  Then  the  process  of  proof 
becomes  fully  attended  to. 

Inductive  Proof.  —  The  other  form  of  proof,  the  induc- 
tive, consists  in  counting  instances,  in  determining  how 
often  the  conclusion  is  true.  If  in  the  past  a  solution 
has  worked  on  every  occasion,  we  are  prepared  to  accept 
it  as  true.  The  proof  on  this  side  lies  in  the  actual  study 
of  past  cases  or  in  experimental  repetition  and  verifica- 
tion of  the  conclusion.  From  a  study  of  the  \ital  statis- 
tics one  knows  inductively  that  all  men  die.  One  knows 
that  an  aeroplane  will  fly,  because  it  has  flown.  The 
whole  proof  is  one  of  assuming  that  what  has  happened 


414  FUNDAMENTALS    OF   PSYCHOLOGY 

will  happen.  In  one  sense  the  two  proofs  tend  to  come 
together,  since  of  the  empirical  proofs  only  those  are  ac- 
cepted that  are  in  every  way  similar,  that  can  be  referred 
to  the  same  general  principle.  On  the  other  hand,  the 
general  principles  that  constitute  the  major  premises  of 
syllogisms  and  the  accepted  truths  are  probably  in  the 
last  analysis  derived  from  experience,  but  experiences 
coordinated  and  tested  by  particular  applications  and 
by  their  harmony  with  other  general  principles.  A 
general  principle  frequently  starts  as  the  result  of  a  few 
observations,  is  tested  by  other  observations,  then  is  com- 
pared with  other  general  principles  that  have  also  been 
suggested  and  tested  by  other  single  observations,  and,  if 
all  harmonize,  it  gradually  comes  to  be  generally  accepted. 
In  most  subjects  controversies  over  general  principles  are 
current  at  all  times,  because  each  is  in  harmony  with  cer- 
tain experiences  and  out  of  harmony  with  others.  Settle- 
ment comes  with  more  accurate  analysis  of  the  problem, 
with  more  careful  study  of  the  facts,  and,  where  experi- 
ment is  possible,  by  making  crucial  tests  of  each.  But 
in  no  case  is  it  possible  to  say  that  organized  previous 
experience  has  not  played  some  part  in  the  proof,  nor  is  it 
possible  to  assert  that  observation  of  particular  experi- 
ences, induction,  shall  not  have  played  some  part.  When 
reference  to  generalized  old  experience  is  more  in  evi- 
dence, the  proof  is  called  deductive ;  when  particular 
cases,  statistics,  or  experiments  play  the  larger  part,  the 
proof  is  known  as  inductive,  but  neither  can  be  com- 
pletely divorced  from  the  other. 

That  the  stages  of  reasoning  may  be  as  we  have  stated 
them  :  (i)  the  presentation  of  the  problem  that  comes  by 


REASONING         '  415 

a  thwarting  of  the  progress  of  action  or  of  thought,  (2)  the 
judgment  or  analysis  of  the  problem  into  its  elements  and 
the  reference  of  each  to  its  appropriate  class  or  concept, 
(3)  the  inference  or  discovery  of  the  solution  by  much 
casting  about,  and  finally  (4)  proof,  may  be  seen  by  a 
study  of  the  way  in  which  Darwin  and  Wallace  developed 
their  doctrine  of  natural  selection.  It  happens  that  in 
this  case  two  men,  travelling  independently  practically 
the  same  course,  arrived  at  the  same  conclusion,  and  we 
have  the  process  recorded  by  one  of  them  and  confirmed 
by  mutual  friends.  Dr.  Wallace,^  in  modestly  disclaim- 
ing any  priority  to  Dar^vin  in  the  discovery,  traces  in  a 
paper  before  the  Linnaean  Society  the  facts  that  led 
both  to  the  discovery  of  the  idea  and  to  its  statement. 
First  with  reference  to  the  formulation  of  the  problem : 

"  First  (and  foremost  as  I  beHeve)  both  Darwin  and 
myself  became  ardent  beetle-hunters.  Now  there  is  cer- 
tainly no  group  of  organisms  that  so  impresses  the  col- 
lector by  the  almost  infinite  number  of  its  specific  forms, 
the  endless  modifications  of  structure,  shape,  color,  and 
surface-markings  that  distinguish  them  from  each  other, 
and  their  innumerable  adaptations  to  diverse  environ- 
ments. .  .  .  Again,  both  Darwin  and  myself  had,  what 
he  terms  '  the  mere  passion  of  collecting.'  ...  I  should 
describe  it  rather  as  an  intense  interest  in  the  mere 
variety  of  Hving  things  —  the  variety  that  catches  the 
eye  of  the  observer  even  among  those  which  are  very 
much  aHke  but  which  are  soon  found  to  differ  in  sev- 
eral distinct  characters.     Now  it  is  this  superficial  and 

^  The  Origin  of  the  Theor/  of  Natural  Selection,  by  A.  R.  Wallace, 
Pop.  Sci.  ^Monthly,  vol.  Ixxiv,  pp.  398  flf. 


4l6  FUNDAMENTALS    OF   PSYCHOLOGY 

almost  childlike  interest  in  the  outward  form  of  li\dng 
things  which,  though  often  despised  as  unscientific, 
happened  to  be  the  only  one  which  would  lead  us  towards 
a  solution  of  the  problem  of  species.  ...  It  is  the 
constant  search  for  and  detection  of  these  often  unex- 
pected differences  between  very  similar  creatures,  that 
gives  such  an  intellectual  charm  and  fascination  to  the 
mere  collection  of  these  insects  ;  and  when,  as  in  the  case 
of  Darwin  and  myself,  the  collectors  were  of  a  specula- 
tive turn  of  mind,  they  were  constantly  led  to  think  upon 
the  '  why  '  and  the  ^  how  '  of  all  this  wonderful  variety 
in  nature  —  this  overwhelming,  and,  at  first  sight,  pur- 
poseless wealth  of  specific  forms  among  the  very  humblest 
forms  of  Hfe.  .  .  .  Then,  a  Httle  later  ...  we  became 
travellers,  collectors,  and  observers  in  some  of  the  richest 
and  most  interesting  portions  of  the  earth  ;  and  we  thus 
had  forced  upon  our  attention  all  the  strange  phenomena 
of  local  and  geographical  distribution,  with  the  numerous 
problems  to  which  they  give  rise.  Thenceforward  our 
interest  in  the  great  mystery  of  how  species  came  into 
existence  was  intensified,  and  —  again  to  use  Darwin's 
expression  —  *  haunted  '  us. 

''  Finally,  both  Darwin  and  myself,  at  the  critical 
period  when  our  minds  were  freshly  stored  with  a  con- 
siderable body  of  personal  observation  and  reflection 
bearing  upon  the  problem  to  be  solved,  had  our  attention 
directed  to  the  system  of  positive  checks  as  expounded  by 
Malthus  in  his  '  Principles  of  Population.'  The  effect 
of  this  was  analogous  to  that  of  friction  upon  a  specially 
prepared  match,  producing  that  flash  of  insight  which  led 
us  immediately  to  the  simple  but  universal  law  of  the 


REASONING  417 

'  survival  of  the  fittest,'  as  the  long-sought  effective 
cause  of  the  continuous  modification  and  adaptation  of 
living  things." 

This  shows  that  the  problem  had  been  set  for  both  by 
almost  the  same  conditions  and  that  the  solution  had 
been  attained  in  the  same  way,  but  the  method  of  proof 
devoted  to  the  suggestion  was  altogether  different. 
Darwin  spent  thirty  years  in  collecting  evidence  and  in 
writing  out  the  evidence  with  only  one  mention  of  his 
theory  to  Sir  Charles  Lyell.  Wallace,  on  the  contrary, 
sat  down  at  once,  wrote  a  sketch  of  his  theory,  and, 
curiously  enough,  sent  it  to  Darwin  with  the  request  that 
it  be  pubKshed.  On  the  advice,  of  friends  Darwin  pre- 
sented the  paper  with  a  sketch  of  his  own  theory  to  a 
meeting  of  the  Linnaean  Society  July  i,  1858.  Darwin 
said  that  even  the  words  of  Wallace's  paper  were  so 
nearly  like  his  own  that  one  might  have  supposed  that 
he  must  have  seen  it  before  he  wrote.  Wallace  empha- 
sizes the  influence  of  similar  circumstances  upon  the 
common  result : 

"  This  view  of  the  combination  of  certain  mental 
faculties  and  external  conditions  that  led  Darwin  and 
myself  to  an  identical  conception  also  serves  to  explain 
why  none  of  our  precursors  or  contemporaries  hit  upon 
what  is  really  so  very  simple  a  solution  of  the  great 
problem.  .  .  .  And  now  to  recur  to  my  own  position, 
I  may  be  allowed  to  make  a  final  remark.  I  have  long 
since  come  to  see  that  no  one  deserves  either  praise  or 
blame  for  the  ideas  that  come  to  him.  .  .  .  Ideas  and 
beliefs  are  certainly  not  voluntary  acts.  They  come  to 
us  —  we  scarcely  know  how  or  whence,  and  once  they 


4l8  FUNDAMENTALS    OF   PSYCHOLOGY 

have  got  possession  of  us  we  cannot  reject  or  change  them 
at  will.  It  is  for  the  common  good  that  the  promulga- 
tion of  ideas  should  be  free  —  uninfluenced  by  either 
praise  or  blame,  reward  or  punishment." 

In  this  sketch  Wallace  marks  out  explicitly  three  of 
our  stages,  —  the  arousal  of  the  problem,  the  hitting  upon 
the  solution,  and  the  proof.  The  second,  the  analysis 
of  the  problem  or  judgment,  can  be  seen  implicitly  in  the 
many  forms  that  the  problem  took  as  the  how  and  why  of 
the  species  became  prominent  at  different  times.  Ob- 
servation will  show  that  any  clearly  formulated  bit  of 
reasoning  takes  essentially  the  same  course.  Most  of 
the  thinking  of  our  daily  life,  even  the  important  deci- 
sions, stop  with  the  impUcit  belief.  The  formal  justifica- 
tion of  the  conclusion  is  not  made.  But,  as  was  seen, 
the  unformulated  but  organized  earher  experience  is  at 
work  in  accepting  or  rejecting  these  conclusions  through 
the  immediate  belief  processes,  just  as  it  is  in  the  more 
formal  operations.  The  warrant  is  the  same  although 
the  form  in  which  it  is  expressed  is  different. 

In  reasoning,  then,  we  see  an  advance  made  upon  the  ac- 
cumulated knowledge,  but  an  advance  that  is  always  made 
possible  and  controlled  by  that  accumulated  knowledge. 
One  understands  the  new  presentation  and  the  new 
difficulties  in  terms  of  the  organized  old  experiences,  the 
types  and  concepts  ;  one  obtains  suggestions  for  new  solu- 
tions on  the  basis  of  analogies  with  the  old ;  and,  when 
obtained,  the  suggestions  for  new  solutions  are  justified 
and  tested  in  advance  of  actual  use  in  the  light  of  the 
organized  knowledge.  While  new  experiences  and  new 
trials  are  constantly  increasing  the  sum  total  of  knowl- 


REASONING  419 

edge,  it  is  only  by  \irtue  of  the  pre\dous  accumulations 
and  organizations  that  the  new  can  be  understood  and 
that  one  may  venture  to  test  the  new  suggestions  in 
action  with  even  fair  assurance  of  success. 

REFEREkcES 

TiTCHENER :  Experimental  Psycholog>'  of  the  Thought  Processes. 

Dewey  :  How  We  Think. 

Dewey  :  Studies  in  Logical  Theor>'. 

PiLLSBURY :  The  Psychology  of  Reasoning. 


CHAPTER  XII 
INSTINCT 

Very  much  of  the  motor  and  some  important  parts 
of  the  affective  and  sensory  activity  of  the  individual, 
whether  man  or  animal,  are  not  acquired,  but  are  present 
at  birth  or  develop  at  some  time  during  the  life  of 
the  individual  without  being  learned.  We  assumed  in 
connection  with  the  discussion  of  the  nervous  system 
that  numbers  of  synapses  were  open  at  birth  and  that 
these  determined  the  course  of  many  of  the  early  re- 
sponses. These  reflexes  are  active  at  all  times  and  play 
a  most  important  part  in  keeping  the  organism  alive 
until  learning  is  possible,  and  throughout  life  may  be 
said  to  care  for  the  essential  activities.  Respiration, 
the  beat  of  the  heart,  and  all  of  the  activities  of  the 
alimentary  canal  go  on  of  themselves.  They  do  not 
require  thought  to  continue  them  and  cannot  be  stopped 
voluntarily.  The  list  of  reflexes  might  be  continued 
indefinitely,  as  they  include  the  regulation  of  all  of  the 
vital  processes  and  the  adjustment  of  the  skeletal  mus- 
cles to  the  demands  of  simple  stimuli. 

Definition  of  Instinct.  —  Closely  related  in  many 
ways  to  the  reflexes  and  also  part  of  the  natural  endow- 
ment of  man  are  other  movements  and  tendencies  to 
movement,  the  instincts.  Under  this  head  are  included 
a  large  number  of    different  processes,   activities    and 

420 


INSTINCT  421 

tendencies  to  activities.  So  general  has  been  the  use  oi 
the  word,  in  fact,  that  some  writers  desire  to  give  it 
up  as  too  vague.  However,  so  many  important  facts 
may  be  grouped  under  the  term,  and  the  series  of  activi- 
ties it  describes  is  so  important,  that  it  seems  much 
better  to  retain  the  word  and  to  state  clearly  just  what 
it  is  and  what  it  is  not  to  mean.  Three  fairly  dis- 
tinct meanings  of  the  word  instinct  are  current.  The 
first  is  to  designate  a  more  complicated  reflex,  or  one 
that  in  its  variabihty  in  some  degree  approaches  the 
voluntary  act.  Thus,  the  pecking  at  a  grain  of  corn 
by  a  newly  hatched  chick,  and  the  complicated  series  of 
movements  by  which  it  breaks  its  way  out  of  the  shell, 
are  instincts  of  the  first  type.  They  are  more  compli- 
cated than  the  reflex,  involve  a  greater  number  of  muscles, 
and  a  larger  number  of  movements  in  a  series.  The  line 
between  instincts  and  reflexes,  when  instinct  is  used  in 
this  sense,  is  difficult  to  draw.  Just  how  compHcated 
a  reflex  must  be  to  be  an  instinct  is  not  easy  to  say. 
It  has  sometimes  been  asserted  that  instincts  are  more 
purposive,  reflexes  more  mechanical,  but  even  then  the 
matter  is  not  made  much  clearer,  since  most  reflexes 
as  well  as  instincts  have  a  purpose  even  if  reflexes  are 
explained  by  mechanism.  Again,  there  is  always  an 
impHcation  in  instinct  that  we  are  dealing  with  some- 
thing that  is  or  might  be  conscious,  that  is  like  volun- 
tary action.  But  this  is  mostly  an  analogy,  and,  since 
instincts  are  very  frequently  not  conscious,  or  we  can 
only  infer  that  they  are  conscious,  even  this  criterion 
is  not  susceptible  of  accurate  appHcation.  Instinct  in 
this  sense  is  a  movement  made  in  response  to  a  stimulus 


422  FUNDAMENTALS    OF   PSYCHOLOGY 

or  a  group  of  stimuli  as  a  result  of  inherited  connec- 
tions in  the  nervous  system,  a  movement  more  compli- 
cated than  a  reflex,  either  in  the  number  of  stimuH  that 
call  it  out,  or  in  the  number  of  muscles  that  are  coordi- 
nated in  its  execution.  In  many  minds,  but  subordinate 
to  this  distinction,  is  the  further  implication  that  the  in- 
stinct is  purposive,  and  more  Uke  voluntary  or  conscious 
movement  than  the  reflex. 

A  second  use  of  the  word  instinct  is  much  broader 
and  refers,  not  to  some  specific  response,  but  to  the 
fact  that  movements  which  may  vary  with  surroundings 
are  carried  out  to  the  attainment  of  some  general  end. 
This  covers  a  much  larger  number  of  instincts  in  man 
and  the  higher  animals  than  does  the  single  simple  act 
or  group  of  acts.  Thus,  a  simple  unmodified  instinct 
is  that  of  the  soHtary  wasp  noticed  by  Fabre  and 
quoted  by  Hobhouse  as  follows :  ^'  A  soHtary  wasp, 
Sphex  flavipennis,  which  provisions  its  nest  with  small 
grasshoppers,  when  it  returns  to  the  cell  leaves  the  vic- 
tim outside,  and  goes  down  for  a  moment  to  see  that  all 
is  right.  During  her  absence  M.  Fabre  moved  the 
grasshopper  a  little.  Out  came  the  Sphex,  soon  found 
her  victim,  dragged  it  to  the  mouth  of  the  cell,  and  left 
it  as  before.  Again  and  again  M.  Fabre  moved  the  grass- 
hopper, but  every  time  the  Sphex  did  the  same  thing, 
until  M.  Fabre  was  tired  out." 

Variation  in  Instinct. — As  opposed  to  this  rigidly 
determined  series  of  movements,  most  instincts  •  show 
considerable  variation  and  reach  the  final  end  by  vari- 
ous ways.  The  hunting  instinct  of  a  cat,  as  exhibited 
in  catching  and  kiUing  mice  or  birds,  adapts  itself  to 


IXSTI^-CT  423 

the  circumstances.  Only  the  crouching  as  the  prey  is 
approached  and  perhaps  the  final  spring  are  even  approxi- 
mately uniform.  The  cat  usually  plays  with  the  mouse 
after  it  is  caught,  but  even  this  is  not  a  mere  mechanical 
repetition  of  the  same  movement  or  series  of  movements. 
The  resemblance  between  acts  at  dift'erent  times  is  at 
best  general,  and  the  reaction  is  to  a  number  of  separate 
stimuli  each  of  which  calls  out  a  separate  act,  and  the 
whole  series  is  bound  together  by  the  general  end. 
Probably,  even  here,  each  separate  act  is  the  result  of  a 
definite  stimulus,  but  the  connecting  link  that  makes 
the  whole  a  single  act  is  found  in  the  preparedness 
induced  in  the  animal  by  one  act  which  makes  it  more 
readily  affected  by  a  stimulus  of  the  same  group  rather 
than  by  any  other.  The  whole  may  be  pictured  as 
held  together  by  an  inherited  tendency  for  the  acts  of 
the  entire  series  to  respond  in  succession  to  defijiite 
sorts  of  stimuh.  But  there  is  much  variety  in  the  way 
in  which  the  end  is  reached,  due  apparently  to  the  fact 
that  instead  of  preparing  the  way  for  one  set  of  responses 
alone,  a  number  of  responses,  each  of  which  may  lead 
to  the  desired  end,  are  rendered  more  easy.  WTienever 
a  stimulus  presents  itseh  that  excites  any  of  the  group 
of  miovements,  the  way  is  opened  for  carr}ing  out  all 
of  the  others. 

A  third  common  use  of  the  word  instinct  covers  a 
class  of  actix-ities  which  are  still  less  definite  in  character. 
In  the  extreme  instances  of  this  class  little  is  determined 
by  inheritance  other  than  that  the  desired  end  shah 
be  attained.  The  attainment  may  be  by  any  method 
that  pre\dous  experience  or  the  acquired  habits  shall 


424  FUNDAMENTALS    OF   PSYCHOLOGY 

dictate.  Here  belong  very  many  if  not  most  of  the 
complicated  instincts  manifested  by  the  human  adult. 
Acquisitiveness,  combativeness,  sympathy,  and  the 
great  mass  of  instincts  that  may  be  regarded  as  protect- 
ing the  human  individual,  the  family,  and  the  social 
group  are  constituted  of  movements  that  have  no  regu- 
larity, but  nevertheless  drive  the  individual  to  a  fairly 
definitely  prescribed  end.  Thus,  we  speak  of  mating 
as  an  instinct,  but  the  preliminary  instinctive  responses 
of  coyness,  and  the  whole  series  of  courting  activities, 
whether  in  the  higher  animals  or  in  man,  are  indefinite. 
At  the  more  reflex  end  of  this  class  are  movements  that 
seem  to  be  directed  toward  a  definite  end,  but  the  separate 
responses  are  not  each  dependent  upon  the  preceding 
act  and  the  stimulus,  but  are  complex  mixtures  of  learned 
movements  with  a  few  reflexes.  In  simplest  form  the 
third  class  is  different  from  the  second  only  in  the  fact 
that  movement  and  the  stimulus  are  not  so  closely 
joined.  One  of  several  responses  may  be  made  to 
the  stimulus.  Again,  one  movement  of  the  series  does 
not  follow  so  mechanically  upon  the  preceding.  Finally, 
the  end  is  more  in  evidence.  This  end  may  be  foreseen, 
although  the  reason  for  the  dominance  of  that  end  or 
purpose  is  usually  not  appreciated.  At  the  other 
extreme  of  this  third  class,  what  is  instinctive  is  the 
pleasure  that  accompanies  the  attainment  of  the  purpose 
rather  than  the  concatenation  of  movements  that  shall 
lead  to  that  end.  The  acts  made  when  one  sees  a  beggar 
may  vary  from  giving  money  to  turning  away  as  quickly 
as  possible,  but  the  feeling  of  pain  that  impels  to  some 
action  is  due  to  inherited  causes.     The  term  instinct, 


INSTINCT 


425 


then,  is  used  to  indicate  all  acts  whose  conditions  are 
inherited.  It  matters  not  whether  those  acts  may  be 
referred  to  specific  inherited  connections  in  the  nervous 
system  or  whether  the  act  is  the  result  of  striving  for 
an  end  which  some  innate  predisposition  compels  the 
indi\ddual  to  strive  for,  and  whose  attainment  gives 
pleasure,  ^\llile  this  definition  is  broader  than  that 
expKcitly  given  by  many  psychologists,  all  extend  the 
term  in  practice  to  cover  acts  that  belong  only  to  our 
broadest  class.  At  present  most  men  incline  to  make 
instincts  primarily  reflexes  of  greater  complexity,  and 
to  reduce  as  many  as  possible  to  the  simpler  forms  of 
response.  This  is  the  more  satisfactory,  as  it  reduces 
to  a  minimum  the  natural  tendency  to  vagueness  and 
the  introduction  of  mystical  forces.  Even  where 
instincts  cannot  be  explained  in  this  simplest  way, 
there  is  no  need  to  resort  to  the  mystical,  since  the  dis- 
positions and  preparatory  irradiations  may  all  be  as- 
sumed to  be  due  to  the  inheritance  of  specific  dispositions 
in  the  nervous  system,  even  if  we  cannot  at  present  say 
exactly  in  what  they  consist. 

Classifications  of  Instinct.  —  The  specific  instincts  are 
differently  classified,  and  no  complete  agreement  exists 
as  to  what  shall  be  regarded  as  instinctive,  even  when 
the  definitions  have  been  settled.  MacDougall  limits 
instincts  to  flight,  repulsion,  curiosity,  pugnacity,  ^\i- 
abasement,  self-assertion,  and  the  parental  instinct 
(under  which  are  placed  care  of  the  child,  sympathy 
as  an  outgrowth  of  care  for  the  offspring,  and,  by  devel- 
opment, moral  indignation).  Minor  instincts  are  re- 
production, gregarious  instincts,  construction.     Watson 


426  FUNDAMENTALS    OF    PSYCHOLOGY 

in  his  study  of  ammals  has  eleven  classes,  —  locomotion, 
obtaining  food,  shelter,  rest,  play,  sleep,  taken  together 
as  the  basis  for  the  daily  and  seasonal  routine ;  sex, 
defense  and  attack,  migration,  mimicry,  vocalization; 
and  two  less  definite  groups.  Some  add  more,  others 
question  some  of  these,  but  there  is  probably  no  chance 
of  close  agreement  among  all  as  to  just  how  many  groups 
there  are,  or  even  what  specific  acts  shall  be  included 
in  any  group. 

We  may  do  best  to  make  a  general  classification  with 
reference  to  the  end  that  the  act  subserves,  rather  than 
to  the  specific  character  of  the  particular  instinct.  One 
of  the  most  convenient  divides  instincts  into  three 
classes :  i .  those  which  preserve  the  Hf e  and  provide 
for  the  welfare  of  the  individual ;  2.  those  which  provide 
for  the  continuance  of  the  race  and  for  the  family ;  and 
3.  those  which  make  for  the  welfare  of  the  tribe  or  of 
the  social  unit.  Some  of  the  acts  belong  to  more  than 
one  class,  —  in  fact,  no  one  of  the  second  or  third  would 
be  possible  without  the  first,  —  but  the  division  is 
convenient  in  general  and  may  serve  as  a  guide  through 
the  maze. 

Individual  Instincts.  —  Among  the  individual  instincts 
we  have  those  necessary  to  care  for  the  individual  in 
the  early  stages  of  fife.  One  of  the  best  instances  is 
found  in  the  pecking  its  way  out  of  its  shell  by  the  young 
bird.  This  instinct,  according  to  Craig,  is  always  car- 
ried out  in  very  much  the  same  way  although  involving 
a  number  of  separate  movements,  pecking  itself,  and  so 
turning  in  the  shell  that  the  shell  may  be  broken  in  a 
continuous  ring.     Here,  too,  belong  the  first  movements 


INSTINCT  427 

of  taking  food,  which  make  their  appearance  ahnost 
at  once,  and  change  their  character  as  the  needs  of  the 
organism  develop.  Other  indi\ddual  instincts  are  in- 
volved in  locomotion,  walking,  flying,  or  swimming, 
the  care  of  the  body  in  matters  of  cleanliness,  the  preen- 
ing of  the  feathers  by  the  bird,  licking  the  body  by 
cats,  dogs,  etc.,  tjie  persistent  hunt  for  parasites  that 
seems  to  occupy  a  large  part  of  the  spare  time  of  all 
monkeys  and  apes,  stalking  game,  fighting,  flight  from 
larger  animals,  in  sum  an  imposing  list.  In  man  the 
number  is  no  less  great,  and  each  of  the  simpler  names 
includes  in  most  cases  a  larger  number  of  different 
acts.  Some  of  the  more  complicated  acts  that  play  a 
large  part  in  determining  the  character  of  the  man  and 
many  of  his  most  important  qualities  are  flight  or  fear, 
pugnacity,  collecting  materials  of  all  kinds  from  money 
to  postage  stamps,  rivalry  mth  its  accompaniment  of 
en\y,  curiosity,  and,  possibly,  constructiveness,  although 
the  latter  may  be  a  compound  of  other  instincts.  Simi- 
larly, laughing  and  weeping  with  simple  forms  of  vocali- 
zation probably  belong  among  the  instincts. 

These  instincts  seem  to  be  present  in  some  degree  in 
all  men.  Some,  however,  are  more  striking  for  their 
universality,  others  because  they  are  present  in  such 
different  degrees  in  different  indi\dduals.  Thus,  fears 
show  themselves  in  practically  all,  although  to  be  sure 
in  different  forms  and  in  different  degrees.  In  most 
cases  these  are  not  to  be  explained  from  experience 
and  many  are  absurd  in  the  light  of  experience.  Why 
a  grown  woman  should  be  so  startled  by  a  mouse, 
why  a  man  should  make  such  exaggerated  responses 


428  FUNDAMENTALS    OF   PSYCHOLOGY 

when  a  harmless  snake  wraps  itself  around  his  ankle, 
are  hard  to  understand  in  the  light  of  experience  alone. 
Similar  are  the  trembling  at  looking  over  the  edge  of 
a  precipice  from  behind  a  perfectly  secure  railing,  the 
fear  of  the  dark,  of  caves  and  strange  places,  of  the  dead, 
and  hosts  of  others  that  the  reader  may  supply  from 
his  own  experience.  In  the  development  of  a  child, 
these  fears  come  one  after  another  and  frequently  disap- 
pear almost  as  suddenly  as  they  appear.  For  a  few 
weeks  or  months  a  child  will  be  afraid  of  furs,  then  the 
fear  disappears  and  fondness  for  it  replaces  the  fear. 
A  cat  may  suddenly  become  an  object  of  terror  and  later, 
without  other  experience  of  cats,  may  arouse  all  signs 
of  pleasure.  Thus,  the  early  life  may  be  a  constant  suc- 
cession of  fears  that  come  apparently  with  the  stages 
of  development  of  the  nervous  system.  Interesting, 
too,  it  is  to  note  the  tendency  of  those  fears  to  become 
exaggerated  in  diseased  conditions  of  the  central  ner- 
vous system.  Here  we  find  fear  of  open  places  that 
leads  the  victim  to  sKnk  around  the  sides  of  parks  rather 
than  walk  across  them  (agoraphobia),  and  also,  the  op- 
posite tendency,  to  fear  all  closed  places,  to  avoid  rooms 
and  narrow  streets,  and  to  feel  at  home  only  in  the  open 
(claustrophobia).  These  are  but  two  of  many  morbid 
fears. 

Among  the  instincts  that  aid  to  make  up  the  individual 
character  by  the  amount  they  contribute  to  the  sum 
total  of  his  instincts  are  pugnacity,  the  tendency  to 
accumulate,  and  curiosity.  The  degree  of  pugnacity 
is  one  of  the  most  important  individual  characteristics. 
It  varies  from  the  extreme  in  a  tendency  to  domineer 


INSTINCT  429 

over  every  one,  through  a  moderate  degree  of  self- 
assertion,  to  an  extreme  in  the  weakHng  who  never 
asserts  himself.  The  one  man  never  admits  that  he  is 
wrong,  will  never  see  that  he  is  beaten,  but  fights  on 
to  the  end.  Tempered  with  proper  discrimination  of 
what  is  worth  fighting  for,  this  constitutes  one  of  the 
elements  in  all  strong  characters  ;  untempered,  it  makes 
the  quarrelsome  bully.  The  man  in  whom  it  is  badly 
developed  is  ready  to  give  up  with  the  first  disappoint- 
ment, if  he  permits  himself  to  get  involved  at  all.  Closely 
related,  if  not  identical,  are  the  qualities  of  courage  and 
cowardice.  The  collecting  instinct  is  not  quite  so  clearly 
demonstrable  as  an  instinct,  but  the  piHng  up  of  hoards 
of  all  kinds  beyond  the  probable  or  even  the  possible 
needs  of  an  individual  seems  to  demand  an  explanation 
other  than  habit.  The  intense  pleasure  which  comes 
with  the  large  accumulation  is  indicative  of  other  than 
acquired  characteristics. 

Curiosity  is  a  striking  character  in  the  attitude  of 
the  higher  animals  as  well  as  of  men.  The  dog,  the  cat 
in  less  degree,  monkeys  in  the  extreme,  show  a  tendency 
to  examine  all  strange  objects.  From  their  acts  one 
might  argue  that  they  were  intent  on  understanding 
them.  Certainly  in  man  there  is  a  pervading  restless- 
ness until  all  unfamihar  objects  and  movements  have 
been  examined  and  explained,  —  an  instinct  that  shows 
itself  early  and  persists  with  increasing  intensity  until 
well  into  old  age.  In  its  simple  forms  in  the  child  or  in 
the  uncultivated  it  impels  an  investigation  of  all  possible 
sources  of  danger  and  pro\'ides  for  the  security  of  the 
individual.     In  its  higher  forms  it  may  well  be  regarded 


430  FUNDAMENTALS    OF   PSYCHOLOGY 

as  the  source  of  very  much  of  man's  desire  for  knowledge 
and  of  the  growth  of  science  developed  from  it.  Much 
of  this  knowledge  is  probably  useless  from  the  practical 
man's  standpoint,  and  in  any  case  the  investigations 
that  lead  to  the  discoveries  are  most  frequently  carried 
out  for  the  sake  of  the  knowledge  itself,  rather  than 
from  any  intention  of  obtaining  practical  benefit.  The 
background  and  foundation  of  the  individual's  character 
are  to  be  explained  in  large  measure  from  the  degree  in 
which  he  has  instincts.  They  determine  in  some  meas- 
ure what  shall  appeal  to  him  and,  in  still  larger  measure, 
the  amount  of  effort  that  he  devotes  to  attaining  the  end 
that  appeals. 

Race  Instincts.  —  No  less  important  in  the  adult  hfe 
are  the  race  instincts.  The  mating  instincts  give  illus- 
tration both  of  the  definite  but  compKcated  response, 
and  of  the  vaguer  movements  determined  only  as  to 
their  end,  or  even  by  the  pleasure  that  comes  from  the 
attainment  of  a  given  purpose,  with  Httle  control  of  the 
method  of  attainment.  The  manner  of  the  manifesta- 
tions of  the  courting  impulses  is,  in  man,  not  at  all  a 
matter  of  conscious  purpose.  The  display  and  boast- 
fulness  of  the  male  on  the  one  hand,  or  his  bashfulness 
in  the  presence  of  a  chosen  member  of  the  opposite  sex, 
on  the  other,  is  in  most  cases  not  intentional,  and  can- 
not be  prevented  at  will.  The  coyness  of  the  maiden 
is  equally  removed  from  voluntary  control.  Even 
more  widespread  in  their  effect  upon  society  are  the 
activities  and  feehngs  involved  in  the  care  of  the  young 
and  in  keeping  together  the  family.  In  man  these  pro- 
cesses are  largely  indefinite.     They  are  guided  by  the 


INSTINCT  431 

pleasure  of  the  parent  in  the  welfare  of  thfe  child.  Most 
of  the  actual  movements  are  learned  through  education 
and  developed  by  habit.  Only  the  pleasure  produced  by 
the  achievement  of  the  end  and  by  the  presence  of  the 
child  is  really  instinctive;  the  rest  is  habit.  In  the 
lower  animals  of  course  the  instincts  are  much  more 
definite,  as  in  the  building  of  the  nest,  in  determining 
the  kind  of  food  that  is  given,  and  the  way  it  shall  be 
given.  Even  here,  however,  much  is  left  to  the  control 
of  circumstances,  for  the  processes  cannot  be  reduced 
to  a  mere  chain  of  reflexes.  In  man  the  continuous  asso- 
ciation and  the  care  for  the  welfare  of  the  members  of 
the  family  constitute  an  important  element  in  the  devel- 
opment of  unselfishness  in  general  and  of  all  the  ideal 
elements  in  character. 

Social  Instincts.  —  The  widest  group  of  instincts,  the 
social,  are  least  often  expressed  as  definite  responses  on 
the  level  of  reflexes,  and  most  frequently  are  merely 
goals  imposed  by  feehngs  of  pleasure  or  the  reverse. 
Simple  gregariousness  is  most  frequently  shown  in  the 
lower  animals  and  is  not  without  its  analogues  in  man. 
The  bison  or  reindeer  or  the  wolf,  under  certain  cir- 
cumstances, seems  to  feel  pleasure  in  merely  being  with 
others  of  his  species.  The  same  instinct  may  be  seen 
in  men  who  feel  pleasure  in  being  in  the  crowd  on  a  city 
street,  even  if  there  be  no  words  spoken  and  no  inter- 
course of  any  kind  with  the  members  of  the  crowd. 
One  may  be  absolutely  alone,  even  avoid  conversation 
with  his  fellows,  and  at  the  same  time  feel  pleasure 
at  their  presence,  or  at  least  feel  a  haunting  and  uncon- 
querable loneKness  when  away  in  the  wilderness  or  where 


432  FUNDAMENTALS   OF   PSYCHOLOGY 

his  fellows  are  not  to  be  found.  Obviously  this  instinct 
finds  no  simple  expression  in  action,  but  is  due  merely 
to  the  pleasant  feehng  of  being  with  others  or  to  the  dis- 
pleasure of  being  alone.  The  individual  may  and  usually 
does  definitely  plan  the  movements  that  will  take  him 
to  a  place  where  people  are  likely  to  be  found,  but  the 
tendency  to  dwell  fondly  upon  the  idea  is  instinctive, 
as  is  also  the  restlessness  that  may  persist  without  aware- 
ness of  its  cause  until  other  human  beings  chance  to  come. 
Still  more  important  is  the  sympathy  that  compels 
us  to  suffer  with  those  who  suffer  even  if  we  are  jealous 
of  those  who  rejoice.  It  is  this  that  makes  for  self- 
sacrifice  in  all  of  its  forms  in  behalf  of  those  beyond  the 
immediate  family ;  it  prevents  cruelty  on  our  own  part 
and  enforces  giving  aid  to  those  who  suffer  at  the  hands 
of  others  or  as  the  result  of  natural  forces.  It  can  be 
seen  in  the  gregarious  animals  who  exert  themselves 
and  even  suffer  in  behalf  of  the  herd,  as  the  male  deer 
are  said  to  form  a  circle  about  the  females  and  the  young 
and  to  risk  their  own  Hves  in  defence  of  the  unit.  This 
instinct  may  be  justified  teleologically,  since  the  survival 
of  the  individual  and  especially  of  the  race  depends 
upon  the  survival  of  the  larger  group.  In  man  the 
most  striking  feature  of  the  instinct  is  the  hmitation  put 
upon  the  group  included  in  its  manifestations.  It 
may  and  has  been  regarded  as  an  extension  of  the  racial 
instinct,  the  instinct  to  protect  the  young,  but  it  includes, 
with  a  force  that  diminishes  with  its  extension,  an  ever- 
widening  group  of  individuals.  The  members  of  the 
particular  social  set  stand  next  to  the  family,  then  the 
individuals  of  the  same  class.     The  further  extensions 


INSTINCT  433 

may  include  the  ever- widening  circle  of  political  divisions, 
it  may  be  drawn  in  some  degree  in  terms  of  religious 
or  party  affiliations,  —  in  fact,  any  common  belief  or 
common  purpose  may  serve  as  the  bond  of  union  within 
which  the  instinct  of  sympathy  may  act.  In  these 
di\dsions  any  common  ideal,  particularly  any  common 
ideal  that  has  opponents,  may  serve  as  the  basis  for  the 
organization  of  a  group  within  which  the  bonds  of  sym- 
pathy are  effective  against  all  outside  it.  These  dif- 
ferent lines  of  organization  may  cross  in  many  ways. 
One's  fellows  in  social  position  may  be  opponents  in 
politics  or  rehgion,  but  the  bonds  of  sympathy  hold  in 
one  respect  or  within  one  group  when  the  same  indi- 
viduals are  separated  in  other  respects.  These  group- 
ings, with  the  consequent  feeHngs,  constitute  the  essential 
facts  in  any  understanding  of  social  organization.  In 
the  widest  form,  the  instinct  includes  all  indi\aduals, 
and  thus  makes  possible  the  highest  development  of 
civiKzation.  Only  in  the  actions  called  out  toward 
members  of  the  accepted  social  group  is  it  possible  to 
assert  that  we  are  deahng  here  with  an  instinct.  What 
shall  constitute  the  group  within  which  the  instinct 
works  is  determined  almost  altogether  by  education 
and  tradition.  With  mutual  knowledge  and  increasing 
numbers  of  common  interests  the  number  of  individuals 
that  may  be  included  in  a  social  unity  has  grown  beyond 
the  bounds  of  any  one  country.  But  on  the  other  hand, 
a  widespread  war  will  suddenly  make  rearrangements 
of  this  grouping,  will  put  beyond  the  pale  many  indi- 
viduals who  have  up  to  that  moment  been  most  inti- 
mate members  of  some  common  group.     The  strong 


434  FUNDAMENTALS    OF   PSYCHOLOGY 

bonds  between  the  socialists  of  all  nations  that  existed 
before  the  great  war  were  suddenly  broken  by  it.  Thus, 
while  instinct  determines  the  treatment  of  the  members 
of  the  common  unit,  education  and  experience  determine 
who  shall  constitute  the  members. 

The  interest  of  man  in  his  fellows  in  general,  and  his 
desire  for  their  approval,  are  also  instinctive.  This  is 
in  the  last  analysis  the  basis  of  social  pressure  of  which 
we  have  made  so  much  in  connection  with  selection  in 
all  of  its  phases.  The  force  exerted  is  not  in  any  sense 
physical.  The  man  may  be  neither  better  nor  worse 
off  on  account  of  the  opinion  held  of  him  by  society, 
but  innate  tendencies  give  the  opinion  of  society  a  force 
that  he  cannot  overcome.  These  influences  hold  the 
man  in  his  accepted  place,  keep  him  to  his  allotted  task 
in  moments  of  weariness,  prevent  eccentric  acts  and 
remarks,  are  the  forces  that  make  society  possible,  even 
if  in  very  many  cases  they  make  convention  dominate 
originality.  In  the  individual  they  serve  as  spurs  to 
many  of  the  activities  with  a  more  remote  purpose,  they 
give  the  ideal  and  unselfish  aim  an  approximation  to 
equal  standing  with  the  material  and  the  selfish. 

We  may  look  to  instinct  for  many  of  the  springs  of 
the  phases  of  conduct  which  we  cannot  understand 
from  the  immediate  circumstances  or  the  earlier  educa- 
tion of  the  individual.  Through  them  he  is  spurred 
to  the  avoidance  of  dangers  that  he  does  not  know,  is 
impelled  toward  the  attainment  of  rewards  that  he  can- 
not foresee.  Where  he  recognizes  the  goal  and  the  pur- 
pose of  the  act,  he,  through  instinct,  is  impelled  to  bodily 
reactions  that  he  does  not  understand  and  which  appar- 


INSTINXT  435 

ently  have  no  meaning  for  the  act  itself.  He  trembles, 
he  weeps,  he  smiles  and  glows  with  warmth,  adjusts  his 
tones  to  the  mournful  or  the  exultant  key,  all,  so  far 
as  he  can  see,  without  reason.  The  insect  lays  its  eggs 
and  pro\^des  for  the  nourishment  and  protection  of  its 
young  which  in  many  cases  it  is  never  to  see.  In  man 
the  acts  necessary  for  the  propagation  of  the  species 
are  ^\'ith  more  knowledge  of  the  purpose,  but  neverthe- 
less many  of  the  details  of  conduct  in  that  connection 
can  be  given  no  explanation  from  experience  alone,  and  the 
strength  of  the  impulses  can  be  understood  only  from 
forces  beyond  experience,  and  often  opposed  to  reason. 
Balancing  these  in  many  respects  are  the  social  instincts 
which  enlarge  the  circle  of  objects  of  instinctive  acts 
and  make  the  individual  sensitive  to  the  demands  of 
the  community  with  its  laws  and  traditions. 

Instinct  and  Learning.  —  It  must  be  remembered 
throughout  that  instincts  never  show  themselves  in 
isolation  or  in  pure  form.  They  are  always  mixed  with 
the  reflexes  on  the  one  side,  and  with  habit  and  even 
with  reason  on  the  other.  The  distinction  between 
reflex  and  instinct  is  hard  to  draw.  Even  when  it  has 
been  decided  that  an  activity  belongs  to  the  class  of 
instincts,  reflexes  are  always  present  to  determine 
the  execution  of  the  individual  acts.  Almost  if  not 
quite  all  instinctive  acts  are  also  influenced  by  learning. 
Even  so  simple  an  act  as  the  chick's  pecking  at  a  grain 
of  corn  is  not  performed  the  first  time  in  full  perfection 
and,  in  the  more  compHcated  processes,  the  instinctive 
and  experiential  factors  can  with  difficulty  be  isolated. 
In  one  set  of  experiments  the  first  attempts  at  pecking 


436  FUNDAMENTALS    OF   PSYCHOLOGY 

on  the  second  day  of  the  chick's  life  gave  ten  correct 
responses  out  of  fifty.  This  increased  to  an  average 
of  a  Httle  less  than  forty  by  the  seventh  day,  from  which 
stage  the  progress  was  comparatively  slow.  While 
mere  growth  with  age  is  important,  still  practice  is 
necessary  in  all  cases,  as  is  shown  in  experiments  by  Breed 
and  Shepard.  They  kept  chicks  blindfolded  for  periods 
varying  from  birth  up  to  five  days  and  found  that  the 
number  of  correct  reactions  the  first  day  of  practice 
was  no  greater  for  the  older  than  for  the  younger,  but 
the  older  made  more  rapid  progress.  By  the  eighth 
day  all  were  on  approximately  the  same  level,  irrespec- 
tive of  the  number  of  days  of  practice.  In  the  more 
compHcated  acts  of  the  higher  animals,  instincts  are  still 
more  dependent  upon  training  and  habit  formation. 
Birds  kept  in  isolation  do  not  ordinarily  develop  the 
peculiar  song  of  their  species,  but  a  new  one.  On  the 
other  hand,  where  young  birds  are  kept  exclusively 
with  older  birds  of  another  species,  they  learn  the  song 
of  that  species  within  the  limits  of  their  own  vocal  capac- 
ity. Even  the  English  sparrow  will  approximate  the 
song  of  canaries  if  kept  near  them  from  birth.  Heredity, 
it  seems,  provides  nothing  but  the  organs  and  the  possi- 
biHty  of  forming  suitable  connections,  together  with 
the  tendency  to  use  the  vocal  apparatus  in  any  necessary 
way.  All  else  is  determined  by  the  practice  of  the  indi- 
vidual, guided  by  the  sounds  that  are  heard. 

In  man,  instinct  is  still  more  mixed  with  habit  and 
all  the  more  rational  and  voluntary  processes.  Language 
is  not  instinctive  as  a  specific  process.  As  in  the  bird, 
what  is  instinctive  is  the  organization  that  makes  sounds 


INSTINCT  437 

possible,  the  instinct  of  making  sounds,  with  no  reference 
to  the  kind,  and  the  desire  for  the  approval  of  his  fellows 
which  makes  it  desire  to  repeat  the  sounds.  These 
together  suffice  to  develop  in  the  child  the  language  of 
the  people  with  whom  it  is  thrown,  by  whom  it  is  reared. 
Even  the  simplest  instinctive  acts  are  not  performed  at 
the  first  trial  in  their  full  perfection.  Both  practice 
and  intelligent  guidance  are  needed  before  great  accuracy 
is  attained.  Here  learning  is  hard  to  separate  from  the 
natural  growth  of  the  individual.  The  sex  instincts 
appear  in  full  vigor  only  as  the  individual  approaches 
maturity.  Other  instincts  come  in  part  at  least  through 
the  growth  of  the  nervous  system ;  they  unfold  one  by 
one  as  the  corresponding  growth  takes  place.  Still,  it 
must  be  insisted  that  practice  plays  a  part  in  the  develop- 
ment of  many  instincts  in  man  as  it  does  in  the  pecking 
of  the  chick  mentioned  above.  Furthermore,  if  the 
instinct  is  not  used  when  it  makes  its  appearance,  there 
is  some  e\idence  that  it  may  fall  into  disuse  and  fail 
to  exhibit  itself  later  when  occasion  arises.  Instinctive 
movements  depend  upon  learning  for  their  develop- 
ment, take  on  much  of  their  specific  form  through  prac- 
tice, and,  in  some  cases  at  least,  disappear  unless  used. 
Imitation  and  Play.  —  Specific  instances  of  the  way  in 
which  instinct  and  learning  cooperate  can  be  well  illus- 
trated by  imitation  and  play,  often  spoken  of  as  instincts. 
As  a  matter  of  actual  observation  we  find  imitation  play- 
ing a  large  part  in  the  Hfe  of  man  and  the  higher  animals. 
On  analysis,  however,  it  is  not  possible  to  say  that  imi- 
tation is  itself  an  instinct.  The  variety  of  movements 
involved  is  too  great  to  bring  it  under  the  head  of  a 


438  FUNDAMENTALS    OF   PSYCHOLOGY 

complicated  reflex,  and,  so  far  as  one  may  regard  it 
as  a  search  for  a  goal  determined  by  the  pleasure  of 
the  attainment  of  the  goal,  nothing  more  is  needed 
to  account  for  it  than  the  general  instinctive  pleasure 
of  social  approval  to  supply  the  end  and  interest  in  the 
other  individuals  of  the  species  and  in  their  acts  to  induce 
attempts  to  perform  the  specific  act.  Thus,  when  the 
child  learns  to  speak,  it  may  be  said  roughly  to  be  through 
imitation,  but  analysis  proves  that  the  child  has  an 
instinct  to  make  sounds  of  no  particular  character. 
When  by  chance  these  result  in  words,  the  parents 
recognize  and  repeat,  and  give  evidences  of  pleasure  that 
lead  the  child  to  attempt  to  say  them  again ;  or  the  child 
may  himself  be  vaguely  conscious  of  the  similarity  of 
the  sounds  he  makes  to  words  that  he  has  heard  and  so 
be  more  interested  in  them  than  in  the  other  sounds. 
In  any  case  it  is  the  instinctive  pleasure  in  sounds  from 
others  of  his  kind,  and  the  approval  they  give  to  his 
own  efforts,  that  lead  to  the  repetition  of  the  sound 
once  made.  Imitation  in  older  individuals  and  of  move- 
ments that  are  already  known  in  their  elements  can  also 
be  traced  to  similar  general  instincts. 

Play  also  is  an  expression  of  many  instincts  rather 
than  of  a  single  one.  The  tendency  to  play  can  be  looked 
upon  as  a  result  of  the  general  tendency  to  action,  to 
motor  discharge.  The  character  of  the  discharge, 
the  particular  play  indulged  in,  is  determined,  in  part 
by  the  environment  and  by  the  general  social  instincts, 
and  in  part  by  a  host  of  particular  instincts.  Thus, 
playing  with  a  doll  is  partly  imitation  of  the  mother, 
partly  an  early  budding  of  the  maternal  instinct ;    the 


INSTINCT  439 

hunting  and  lighting  plays,  the  constructive  plays,  all 
forms  of  rivalry  and  competition  are  but  the  exhibition 
of  different  instincts  under  make-believe  conditions, 
under  circumstances  assumed  to  exist  for  the  sake  of 
the  play.  At  most,  play  is  no  single  instinct  but  the 
expression  of  a  host  of  instincts  under  the  pressure  of  a 
general  tendency  to  act,  to  find  an  outlet  for  a  reserve 
of  energy  under  the  effects  of  stimulation.  The  value 
of  play  in  developing  capacities  through  practice  in 
advance  of  the  actual  necessity  is  obvious. 

The  Origin  of  Instinct.  —  The  origin  of  instinct  is 
primarily  a  problem  for  the  biologist.  Instincts  are 
nervous  dispositions  that  have  been  developed  in  the 
different  species  and  are  then  inherited.  The  way  in 
which  instincts  might  arise  has  attracted  most  attention, 
as  the  inheritance  is  largely  taken  for  granted.  The 
opposing  general  theories  of  evolution,  the  theory  of 
acquired  characters  and  of  natural  selection,  have  been 
appHed  to  its  explanation.  For  psychology  either 
theory  suffices.  It  would  be  easier  to  explain  instinct 
as  the  inheritance  of  the  tendency  to  make  movements 
that  have  been  repeatedly  made  by  the  ancestors,  but 
a  majority  of  the  biologists  are  at  present  sceptical  of 
the  possibihty  of  such  an  inheritance  (the  inheritance 
of  acquired  characters) ,  and  psychology  has  no  evidence 
of  its  own  to  offer  in  its  favor.  Certainly  no  specific 
acts  that  have  been  developed  in  a  high  degree  by  the 
father  exhibit  themselves  in  the  child,  and  when  any 
particular  capacity  of  the  father  can  be  detected  in  the 
child  it  is  doubtful  whether  it  is  not  due  to  an  inheritance 
by  the  father  rather  than  to  his  particular  training. 


440  FUNDAMENTALS    OF   PSYCHOLOGY 

Barring  inheritance  of  acquired  characters,  instincts 
must  be  due  to  the  selection  of  the  individuals  who  chance 
to  develop  those  favorable  to  survival.  The  cause  of 
the  change  in  the  germ  plasm  that  produces  the  favor- 
able instinct  is  not  at  all  determined.  It  may  be  due  to 
some  chemical  action,  as  in  some  cases  it  has  been  shown 
to  be  induced  by  physical  stimuli ;  but  given  the  change, 
however  it  arises,  it  tends  to  persist  in  the  later  genera- 
tions. All  that  the  doctrine  of  natural  selection  asserts 
in  addition  is  that  those  organisms  which  chance  to 
develop  tendencies  to  action  favorable  to  their  survival 
and  to  the  continuance  of  the  species  will  increase  in 
numbers,  and  those  which  fail  to  develop  this  tendency 
will  die  out  and  their  instincts  will  die  with  them.  As  a 
result  of  this  selection  in  the  course  of  the  ages  and 
innumerable  generations  of  individuals,  we  find  man  a 
being  provided  with  many  of  the  structures  essential 
to  his  present  method  of  living,  as  well  as  many  that 
are  left  over  from  stages  in  which  they  may  have  been 
useful,  but  are  now  at  best  not  harmful.  Similarly,  selec- 
tion has  given  a  nervous  system  with  connections  and 
predispositions  that  are  on  the  whole  adequate  to  the 
direction  of  the  bodily  structures,  although  there  are 
some,  those  at  the  basis  of  many  of  the  fears,  e.g.,  that 
might  easily  be  dispensed  with. 

In  conclusion,  we  must  assume  that  there  are  a  number 
of  the  most  fundamental  reactions  and  demands  of  the 
organism  which  are  present  in  it  from  birth  and  serve 
as  a  foundation  for  the  superstructure  of  learning.  In 
part  these  are  specific  acts  or  groups  of  acts,  in  part 
they  make  their  effect  felt  as  ends  towards  which  the 


INSTINCT  441 

organism  must  struggle  by  whatever  movements  it 
may  have  at  its  disposal.  There  seems  to  be  a  possi- 
bility of  making  either  the  movements  that  are  aroused 
through  instinct,  or  the  feehng  that  accompanies  the 
movement,  fundamental  in  the  explanation  of  all  in- 
stincts. In  the  one  case,  each  situation  would  call  out 
a  definite  response,  and,  where  the  obvious  response  was 
lacking,  it  could  be  assumed  that  it  was  still  present  in 
some  obscured  or  unnoticed  form.  On  the  other  hand,  it 
might  be  assumed  that  what  is  instinctive  is  the  feehng,  — 
the  pleasure  that  accompanies  the  instinctively  deter- 
mined proper  end,  and  the  unpleasantness  or  restlessness 
that  persists  until  that  end  is  attained.  As  has  been 
seen,  one  theory  would  hold  very  satisfactorily  for  one 
t>pe  of  instinct,  the  other  just  as  satisfactorily  for  an- 
other. It  seems  more  in  harmony  with  the  facts  and, 
on  the  whole,  to  offer  less  difficulty  for  the  theory  to 
assume  that  both  the  movement  and  the  feeling  are 
accompaniments  or  results  of  the  single  biological  pre- 
disposition. At  the  lower  level  the  movement,  at  the 
upper  levels  the  end  which  asserts  itself  only  because  it 
is  pleasant  when  attained  are  the  more  frequent  charac- 
teristics of  the  instinct.  This  leaves  much  to  be  ex- 
plained, but  it  does  permit  the  use  of  the  word  in  the 
broad  sense,  imphed  if  not  explicitly  adopted,  by  modern 
psychologists. 

In  instinct  we  find  the  source  of  most  of  the  movements 
and  many  of  the  feehngs  that  we  cannot  explain  by 
immediate  stimuh  or  from  the  earher  experience  of  the 
individual.  It  not  merely  provides  the  germ  which  is 
later  developed  into  the  compHcated  movements,  but 


442  FUNDAMENTALS    OF   PSYCHOLOGY 

also  many  of  the  strongest  incentives  that  we  have  in 
connection  with  our  most  complex  voluntary  and  ra- 
tional life.  If  one  ask  why  he  is  afraid  of  the  dark,  why 
the  mysterious  thrills,  the  answer  can  be  given  only  in 
terms  of  instinct.  Similarly,  if  one  ask  why  to  acquire 
wealth,  or  to  invent  a  new  machine,  or  discover  some 
new  truth  should  be  of  almost  universal  appeal,  we  can 
again  reply  only  in  terms  of  instinct.  If  one  seek  an 
explanation  of  why  one  falls  in  love  and  of  many  of  his 
actions,  particularly  of  his  thrills  and  blushings  and 
tones  pecuhar  to  that  state,  one  must  look  to  instinct. 
Finally,  and  most  important  of  all,  the  social  instinct 
suppKes  the  desire  to  be  popular,  to  seek  the  approval 
of  the  fellows  upon  which  depends  the  force  of  social 
convention,  and  which  drives  to  work  when  individual 
need  and  individual  instinct  exhaust  their  impelling 
power.  If  this  extreme  statement  would  seem  to  make 
everything  worth  while  only  because  of  its  instinctive  ap- 
peal, it  must  be  remembered  that  instinct  is  developed, 
modified,  and  even  restrained  through  experience  and 
reduced  to  conventional  type  by  social  pressure,  itself 
an  expression  of  the  social  instinct.  Certain  it  is  that 
very  many  of  the  phenomena  in  connection  with  feel- 
ing and  action  and  particularly  in  emotion  can  be  under- 
stood, if  they  are  to  be  understood  at  all,  only  in  terms 
of  instinct. 

REFERENCES 

McDouGALL :  Social  Psychology. 

Morgan  :  Habit  and  Instinct. 

Watson  :  Animal  Behaviour. 

James  :  Principles  of  Psychology,  vol.  ii,  ch.  24. 


CHAPTER  XIII 
FEELING  AND   AFFECTION 

The  first  of  the  processes  that  are  in  part  explained  and 
in  part  presupposed  in  instinct,  is  feehng,  the  tone  that 
colors  very  many  of  our  mental  states.  The  principal 
difficulty  in  the  discussion  of  feehng  lies  in  the  fact  that 
the  term  has  no  exact  and  definite  meaning,  or  perhaps 
more  truly  has  a  number  of  meanings,  no  two  of  which 
are  altogether  reconcilable  and  which  are  held  by  dif- 
ferent men  of  nearly  equal  authority.  Feeling  was 
originally  used  to  indicate  approxirnately  the  same  mental 
states  as  sensation.  We  still  use  the  term  popularly  as 
S}Tionymous  with  the  sensations  of  touch  and  of  organic 
sensations.  It  is  also  used  to  indicate  any  conscious  state 
which  is  relatively  vague,  e.g.,  to  designate  intuition  as 
opposed  to  the  more  expKcit  ways  of  reaching  conclusions 
by  reasoning.  We  also  use  the  term  technically  for  any 
less  definite  conscious  state.  Thus,  we  talk  of  a  feeling 
of  interest,  a  feeling  of  recognition,  a  feeling  of  belief, 
and  many  similar  states.  These  states  are  definite 
enough  as  ways  of  being  conscious,  but  their  conditions 
are  less  in  exddence  than  those  of  sensation.  The  term 
feeling  is  used  popularly  and  has  been  used  at  different 
times  for  a  number  of  dift'erent  processes  which  have 
nothing  in  common  except  their  vagueness,  either  in  the 
state  itself,  in  its  reference,  or  in  its  conditions. 

443 


444  FUNDAMENTALS    OF   PSYCHOLOGY 

Definitions  of  Feeling  and  Affection.  —  Evidently  we 
cannot  use  the  term  in  all  of  the  ways  enumerated,  and 
we  are  the  more  justified  in  restricting  it  by  the  fact  that 
there  is  a  fair  consensus  of  opinion  among  psychologists 
who  have  written  recently  that  we  shall  use  it  to  designate 
a  single  process  or  pair  of  processes  commonly  known  as 
pleasure  and  pain,  or  more  accurately  pleasantness  and 
unpleasantness.  Since  the  bare  feeling  is  never  found 
alone  but  is  always  accompanied  by  sensation,  it  is  neces- 
sary to  distinguish  the  simple  element  from  the  complex 
of  sensation  and  feeling.  Thus,  in  a  headache  there  is  a 
definitely  locaHzed  sensation  or  mass  of  sensations,  and 
in  addition  we  dislike  the  ache.  The  dislike  itself,  or  the 
form  that  it  takes  as  a  mental  process,  is  the  affection,  the 
unpleasantness.  No  one  would  deny  that  this  is  quite 
different  as  a  conscious  quality  from  the  sensation  itself. 
This  quality  with  its  opposite  is  what  is  defined  as  affec- 
tion. The  complex  of  affection  with  sensation  is  known 
as  a  feeling.  Psychologists  thus  distinguish  affection 
from  feeling  for  their  technical  usage.  Affection  is  the 
bare  fact  that  we  find  an  event  pleasant  or  unpleas- 
"ant,  while  feeTtTTgSyTIse^  to  indicaT^Jthe  complex  of 
seft6*tkrrr"^TTd--rfection!  Thus,  in  the  instance  aboV^, 
£Re  niiire  Ulipleasantness  of  the  experience  connected 
with  the  headache  is  the  affection,  while  feeling  is  the 
term  applied  to  the  total  experience.  What  is  meant  by 
this  state  can  be  understood  by  all,  but  can  be  accurately 
defined  or  described  by  no  one.  In  the  attempt  to  make 
clear  what  is  meant,  we  must  recall  what  was  said  con- 
cerning concepts.  What  we  desire  to  do  is  to  indicate 
a  concept,  which,  together  with  the  concept  of  sensation, 


FEELING   AND   AFFECTION  445 

shall  serve  to  make  possible  a  description  of  the  most 
general  phases  of  our  conscious  life,  and  to  which  we  may 
refer  concrete  states  as  they  present  themselves  to  in- 
dicate certain  aspects  of  many  of  our  mental  processes. 
To  make  this  reference  is  all  that  can  be  done  in  the  way 
of  analysis,  and  is  helpful  in  all  descriptions  and  discus- 
sions. Sensations  or  affections  are  said  to  be  the  elements 
of  consciousness,  but  that  does  not  mean  that  they  are 
ever  found  separately.  All  that  is  meant  is  that  it  is 
possible  to  discover  in  mental  states  a  sensational  phase 
and  an  affective  phase,  —  that  certain  states  are  similar 
by  virtue  of  the  fact  that  they  are  pleasant,  just  as  cer- 
tain others  are  similar  by  virtue  of  the  fact  that  they  are 
green,  and  still  others  in  that  they  are  square.  For 
convenience,  then,  we  have  spoken  of  sensations  as  inde- 
pendent existences  and  will  speak  of  affections  in  some- 
what the  same  way,  as  if  affections  were  elementary 
conscious  states  and  that  mental  states  might  be  com- 
pounded out  of  them,  as  substances  are  compounded  out 
of  chemical  elements. 

Affection  and  Sensation.  —  In  justif>'ing  a  separate 
discussion  of  the  affective  phase  of  consciousness,  we  must 
meet  two  objections.  First,  it  has  been  held  that  feeling 
is  only  a  special  kind  of  sensation  ;  second,  that  affection 
is  not  a  distinct  element  at  all  but  merely  an  attribute  or 
accompaniment  of  sensation.  To  the  first  suggestion  it 
may  be  objected  that  affections  are  unlike  sensations  in 
that  they  have  no  special  sense  organs.  Pleasure  may 
come  as  the  result  of  the  stimulation  of  any  sense  organ, 
and  displeasure  similarly  may  be  the  accompaniment  of 
many  different  kinds  of  stimulations  and  be  excited 


446  FUNDAMENTALS    OF    PSYCHOLOGY 

through  many  different  sense  organs.  The  argument  for 
the  specific  sensations  of  pleasantness  and  unpleasantness 
seems  to  have  been  developed  on  the  assumption  that 
pain  and  unpleasantness  are  identical.  As  we  have 
seen,  there  is  a  special  sense  organ  for  pain  in  the  skin  and 
other  tissues,  and  if  pain  and  unpleasantness  are  to  be 
considered  identical,  the  sense  organ  for  both  is  readily 
suppUed.  As  a  matter  of  fact  pain  and  unpleasantness 
do  not  mean  the  same  thing.  Pain  is  the  specific  sensa- 
tion, and  unpleasantness  the  accompanying  reaction. 
One  may  see  this  most  clearly,  perhaps,  from  the  fact  that 
pain  is  not  necessarily  unpleasant.  Without  speculating 
as  to  the  pleasure  of  martyrs,  we  find  numerous  cases 
in  which  slight  stimulation  of  pain  spots  is  pleasant,  as 
in  the  cold  of  a  bath,  or  the  fascination  of  pressing  gently 
upon  an  inflamed  spot.  While  pain  in  slight  intensity 
may  on  occasion  be  pleasant,  it  is  not  at  all  infrequent 
for  unpleasantness  to  accompany  other  mental  processes 
in  which  there  is  no  excitation  of  a  pain  nerve.  Smells 
are  unpleasant  when  there  is  often  none  of  the  sharpness 
that  represents  the  excitation  of  cutaneous  sense  ends. 
The  odor  of  decaying  flesh  is  unpleasant  in  itself  as  op- 
posed to  the  unpleasantness  of  ammonia  or  chlorine 
which  is  in  part  due  to  the  excitation  of  pain  nerves  in  the 
mucous  membranes  of  the  nasal  passages.  Unpleasant 
combinations  of  colors  or  of  tones  belong  in  the  same  class 
as  do  the  unpleasant  effects  derived  from  unpleasant 
spatial  and  temporal  relations,  the  unpleasant  ideas  from 
social  wrongs,  etc.  One  finds  a  long  list  of  unpleasant- 
nesses that  cannot  be  referred  to  sense  pains. 

If  pain  be  not  identical  with  unpleasantness  and  the 


FEELING  AND   AFFECTION  447 

pain  nerve  be  not  the  organ  of  the  unpleasant  affection, 
still  less  is  it  possible  to  find  a  specific  sense  organ  for 
pleasantness.  It  has  been  suggested  that  tickle  may  be 
the  pleasant  quality  and  that  there  is  a  specific  sense 
organ  of  tickle.  This  latter  statement,  however,  is  very 
questionable.  Tickle  spots  have  now  and  again  been  re- 
ported, but  the  report  has  seldom  been  confirmed,  and 
has  never  been  generally  accepted.  Granted  the  exist- 
ence of  the  tickle  spots,  the  same  objections  hold  to 
identifying  tickle  with  pleasure  as  against  identif}dng 
pain  with  unpleasantness.  Tickhng  may  be  unpleasant 
and  many  different  kinds  of  pleasure  have  no  resemblance 
to  tickhng.  E\idently  even  if  we  grant  the  existence  of 
the  tickle  spots,  pleasure  must  be  something  more  than  a 
pecuHar  cutaneous  sensation,  just  as  unpleasantness  is 
distinct  from  and  in  addition  to  pain. 

Other  objections  to  identifying  aft'ection  with  sensa- 
tion may  be  made  on  the  basis  of  the  accuracy  of  localiza- 
tion of  the  affections.  Sensations  always  have  a  definite 
place,  ^vhile  affection  is  not  definitely  locaHzed.  One  is 
displeased  or  pleased  in  no  particular  part.  Exceptions 
have  been  taken  on  the  basis  of  organic  sensations,  but 
organic  sensations  are  rather  incorrectly  localized  than 
unlocalized.  Another  distinction  that  rests  on  a  slightly 
less  certain  basis  but  is  probably  generally  vaHd  is  that 
sensory  processes  are  more  objective,  while  the  affective 
processes  are  more  subjective.  Sensations  usually  are 
referred  to  the  outside  world,  while  feelings  are  pecul- 
iarly personal,  peculiarly  one's  own. 

Closely  related  to  this  are  differences  with  reference  to 
the  effects  of  attention  and  the  influence  of  recall.     It 


448  FUNDAMENTALS    OF   PSYCHOLOGY 

seems  fairly  well  assured  that  attending  to  a  feeling  tends 
to  diminish  rather  than  to  increase  it,  while,  as  was  seen, 
attention  increases  the  effectiveness  of  sensations.  In 
passing  upon  this  statement,  one  should  be  careful  to 
distinguish  between  attending  to  the  stimulus  or  to  the 
sensation,  and  to  the  mere  accompanying  pleasantness 
or  unpleasantness.  If  one  think  of  an  aching  tooth,  the 
pain  is  increased  and  the  accompanying  unpleasantness 
with  it.  If,  however,  one  attempts  to  introspect,  to  ask 
how  and  why  this  sensation  is  unpleasant,  one  will  be 
likely  to  find  that  the  unpleasantness  diminishes  as  one 
becomes  interested  in  watching  the  feeling,  and  it  may 
disappear  altogether.  An  unpleasant  situation  bravely 
faced  tends  to  lose  much  of  its  unpleasantness.  The  same 
may  be  said  of  pleasantness.  In  practice  a  constant 
search  for  pleasure  defeats  its  end.  As  one  attends  to  a 
pleasure  it  tends  to  diminish.  Lives  spent  in  pleasure- 
seeking  seem  never  to  attain  their  goal.  The  only  way 
to  make  sure  of  pleasure  is  to  keep  in  mind  some  end  to 
be  accomplished  and  let  the  pleasure  come  as  an  incident 
to  its  attainment.  Keeping  pleasure  itself  in  mind  de- 
stroys it,  while  attending  to  the  stimulus  increases  pleas- 
ure as  well.  The  objective  and  subjective  difference 
may  be  said  to  be  one  phase  of  this  influence  of  attention. 
Objective  processes,  when  attended  to,  increase,  while  a 
purely  subjective  process,  particularly  if  that  be  related 
in  some  way  to  attention  itself,  would  not  be  increased. 
If  one  think  of  feeling  as  an  effect  of  attending  to  a  stimu- 
lus, it  would  follow  that  when  attention  was  not  fixed 
upon  a  stimulus,  at  least  one  condition  of  feeling  would 
disappear  and  the  feeling  with  it. 


FEELING  AND  AFFECTION  449 

This  subjective  character  of  feeling  has  also  been  con- 
nected vnth.  another  character  or  alleged  character  of 
feeling,  viz.  that  it  cannot  be  remembered.  It  is  asserted 
with  some  warrant  from  observation  that  feelings  are  not 
recalled.  This  statement  must  be  carefully  guarded  and 
restricted  if  it  is  to  be  accepted.  The  warrant  for  it  is 
to  be  found  in  the  fact  that  feelings  tow^ard  an  event  are 
likely  to  change  between  the  time  the  event  is  experienced 
and  the  time  it  is  recalled.  Thus  a  social  faux  pas  that 
caused  extreme  embarrassment  may  later  arouse  only 
amusement,  and  a  practical  joke  that  was  much  enjoyed 
at  the  time  may  be  recalled  with  chagrin.  The  affection 
alone  is  not  recalled  in  these  cases,  but  the  event  is  re- 
called, and  the  feehng  aroused  depends  upon  the  circum- 
stances at  the  moment  of  recall.  This  does  not  mean  that 
one  cannot  remember  that  one  was  pleased  or  displeased 
on  the  first  occasion ;  on  the  contrary,  but  the  affection  is 
not  reinstated.  The  memory  of  how  one  felt  is  indirect, 
is  in  terms  of  words  or  the  memory  of  the  expression. 
The  feelings  are  not  reinstated  as  the  sensory  elements 
may  be,  but  are  merely  represented  or  meant.  The  feel- 
ing at  the  time  of  recall  is  the  expression  of  the  present  at- 
titude toward  the  event  rather  than  of  the  earlier  attitude, 
the  attitude  when  the  event  was  really  experienced. 
All  together  there  seems  little  probability  that  affections 
are  merely  separate  sensations.  Pain  and  unpleasantness 
are  distinct,  and  pain  seems  the  only  sensation  that  could 
in  any  degree  be  confused  with  either  pleasantness  or 
unpleasantness.  Pleasant  sensations  have  no  existence ; 
i.e.,  there  are  no  sensations  to  which  the  term  pleasant- 
ness could  always  and  regularly  be  applied  that  do  not 

2G 


450  FUNDAMENTALS    OF   PSYCHOLOGY 

have  a  distinct  sensation  quality  in  addition.  To  assume 
that  any  of  these  sensations  could  be  regarded  as  identical 
with  the  feeling  qualities  is  out  of  harmony  with  the  facts 
of  distribution,  as  well  as  with  the  qualities  of  both  sen- 
sation and  feeling.  The  more  definitely  qualitative 
differences,  the  different  influence  of  attention,  and  the 
difference  in  the  way  they  are  affected  in  recall,  all  reen- 
force  this  conclusion. 

The  suggestion  that  affection  might  be  an  attribute 
of  sensation  meets  with  just  as  grave  difficulties.  As 
Kiilpe  has  suggested,  it  is  always  true  of  attributes  that 
when  one  vanishes  or  is  reduced  to  zero,  the  sensation 
also  disappears.  Sensations  with  no  affective  tone  are, 
on  the  contrary,  relatively  common.  A  sensation  may  be 
indifferent  and  still  be  a  sensation,  while  a  sensation  that 
has  no  quality  and  no  intensity  ceases  to  exist.  Also, 
affections  have  attributes  of  their  own  that  vary  inde- 
pendently of  the  attributes  of  sensation,  which  again  is 
inconsistent  with  the  assumption  that  affection  is  merely 
an  attribute  of  sensations.  Affection  has  duration,  in- 
tensity, and  quality,  is  unpleasant  or  pleasant,  although 
it  has  no  extent  or  position.  On  the  affirmative  side  of 
the  question,  it  must  be  granted  that  we  apparently  never 
have  affection  without  some  sensation,  and  so  it  is  not 
an  entirely  independent  entity.  One  never  feels  vaguely 
pleased  or  displeased :  there  is  always  some  sensation  as 
the  occasion  for  the  affection.  In  certain  instances  the 
affection  seems  the  dominant  element  in  consciousness, 
but  slight  observation  indicates  that  there  are  also  sensa- 
tions, usually  of  a  vague  organic  character,  that  serve  as 
the  excitant  of  the  feeling.     But,  as  has  just  been  said, 


FEELING  AND   AFFECTION  45 1 

this  same  sensation  may  at  times  be  present  in  some 
degree  without  any  accompanying  feeling  or,  on  occasion, 
with  a  feeling  of  the  opposite  character.  On  the  whole, 
it  seems  fairly  safe  to  conclude  that  the  qualities  of  pleas- 
antness and  unpleasantness  are  found  in  close  depend- 
ence upon  stimulus  and  sensation,  but  nevertheless 
constitute  what  may  be  regarded  as  an  independent  men- 
tal state,  or,  to  speak  more  conservatively,  as  a  phase  of 
consciousness  which  cannot  be  understood  if  we  regard  it 
as  merely  sensation  alone,  or  as  an  attribute  of  sensation. 
Treating  our  topic  from  the  structural  point  of  view, 
affection  constitutes  a  type  of  mental  process  that  is  dis- 
tinct from  sensation  but  is  nevertheless  dependent  for 
its  existence  upon  sensation,  certainly  upon  the  excita- 
tions that  cause  sensations.  Pleasantness  and  unpleas- 
antness come  as  a  result  of  sensory  excitation  immediate 
or  recalled,  and  these  excitations  produce  sensations  at 
the  same  time  or  a  little  before  they  give  rise  to  the 
affections.  It  is  probably  true  that  no  excitation  gives 
rise  to  an  affection  without  also  arousing  a  sensation. 
The  occasional  periods  of  vague  well-being  or  vague  ill- 
being  without  apparent  sensational  basis  are  rare,  and  in 
all  probability  merely  cases  in  which  the  affective  aspect 
of  consciousness  has  for  the  moment  overshadowed  the 
sensory.  While  affection  is  thus  dependent  upon  the 
same  excitations  as  sensations  and  even  probably  depend- 
ent upon  the  sensations  themselves  for  its  existence,  it  is 
not  a  mere  attribute  or  phase  of  the  sensation  as  are 
quality  and  intensity;  rather  we  must  regard  it  as  a 
separate  mental  state  or  process  with  attributes  of  its 
own. 


452  FUNDAMENTALS    OF   PSYCHOLOGY 

Qualities  of  Affection.  —  Starting  from  this  assump- 
tion, we  may  consider  affection  in  its  relation  to  the 
various  stimuli,  enumerate  its  qualities  and  its  physiolog- 
ical accompaniments,  in  much  the  same  way  as  we  have 
treated  the  cognitive  processes.  First,  with  reference 
to  the  qualities  of  feeling,  it  may  be  asserted  that  there 
are  but  two,  pleasantness  and  unpleasantness.  Many 
objections  have  been  raised  to  this  statement.  In  the 
first  place,  as  has  been  seen,  many  people  mean  alto- 
gether different  kinds  of  mental  processes,  intuitions  and 
what  not,  from  those  that  we  have  admitted  into  the 
class.  These  we  may  exclude  by  mere  arbitrary  defi- 
nition. They  certainly  have  an  existence  and  a  place 
in  psychology,  but  fall  rather  under  reasoning  and  other 
heads  than  under  feeling.  They  simply  are  not  suffi- 
ciently like  the  processes  we  are  discussing  to  make  it  pos- 
sible to  extend  the  term  to  include  them.  Wundt,  using 
the  term  in  somewhat  our  way,  makes  the  suggestion  that 
there  are  many  different  quaHties  of  feeling,  one  for  each 
sensation  and  intellectual  process.  To  this  the  majority 
of  psychologists  stand  in  direct  opposition.  It  is  fre- 
quently asserted  that  purely  sensuous  pleasures,  such 
as  the  pleasures  of  the  table,  are  of  the  same  quality  as 
those  from  a  beautiful  picture  or  from  intellectual  or 
moral  satisfaction.  The  differences  that  strike  one  are 
due  rather  to  the  qualities  of  the  accompanying  sensa- 
tions than  to  the  feeling  qualities  themselves.  If  one 
can  abstract  from  the  sensational  elements,  the  remnant 
of  pure  feeling  is  always  the  same. 

Pleasantness  and  Unpleasantness  the  Only  Qualities 
of  Affection.  —  This  is  opposed  to  many  authorities,  an- 


FEELING   AND   AFFECTION  453 

cient  and  modern,  but  the  distinctions  they  draw  seem 
to  be  based  on  other  than  psychological  grounds.  Thus, 
the  moralist  of  everyday  life  draws  a  distinction  between 
higher  pleasures  and  lower  pleasures.  One  is  the  pleas- 
ure from  the  simple  senses,  the  pleasures  of  eating,  e.g., 
particularly  the  pleasures  from  the  satisfaction  of  the 
simpler  instincts,  while  the  higher  pleasures  are  the 
pleasures  of  the  imagination,  aesthetic  pleasures,  the  pleas- 
ures from  moral  acts.  In  general,  they  are  the  pleas- 
ures which  society  approves,  while  the  lower  pleasures 
are  those  which  are  either  disapproved  or  regarded  as 
morally  indifferent.  This  distinction  is  recognized  by 
every  one.  It  is  at  the  basis  of  one  of  Dr.  Johnson's 
favorite  distinctions  between  pleasure  and  satisfaction. 
Still  it  is  generally  believed  not  to  correspond  to  any  real 
difference  in  psychological  quaHty,  but  rather  to  a  dis- 
tinction based  upon  ethical  considerations.  Sensuous 
pleasure  is  believed  to  be  of  the  same  quahty  as  moral 
pleasure,  the  pleasure  from  a  pleasant  odor  of  the 
same  quality  as  that  from  a  painting  by  an  old  master. 
The  difference  is  to  be  found  in  the  fact  that  one  is 
approved  by  the  connoisseur,  carries  with  it  a  certifi- 
cate of  being  beyond  the  ken  of  the  multitude,  and 
takes  an  added  flavor  from  that  fact,  a  flavor  which 
may  intensify  the  other  quality  but  is  of  the  same 
general  class  or  t}^e.  Other  suggested  qualities  of 
pleasant  and  unpleasant  seem  on  analysis  to  reduce 
to  similar  extraneous  considerations  and  to  leave  but 
two  quaHties,  pleasantness  and  unpleasantness.  In 
general,  one  must  admit  mth  Wundt  that  the  total  feeling 
varies  with  each  stimulation  and  wdth  each  sensation  or 


454 


FUNDAMENTALS    OF    PSYCHOLOGY 


memory  or  other  sort  of  mental  state,  but  the  variation 
is  not  in  the  affection  but  in  the  sensational  accompani- 
ments. The  pleasantness  or  unpleasantness  is,  if  we  are 
to  believe  the  introspections  of  the  large  mass  of  psychol- 
ogists, always  identical,  and  the  differences  that  Wundt 
insists  upon  are  to  be  found  in  the  cognitive  accompani- 
ments.    The  differences  between  sensuous,  aesthetic,  and 


Fig.  89.  —  Schematic  diagram  of  the  relation  of  afifection  to  sensation.  The 
smooth  curve  shows  the  rise  of  sensation  with  intensity  of  stimulus,  the  dotted 
line  the  accompanying  rise  and  fall  of  pleasantness  and  the  increase  of  un- 
pleasantness.    (From  Wundt.) 


moral  pleasures  or  displeasures  are  in  the  occasions  of 
the  affections,  in  the  cognitive  component  of  the  feelings 
rather  than  in  the  affective  elements  themselves. 

The  other  attributes  of  affection  deserve  but  a  sentence. 
The  intensity  of  each  quality  of  affection  varies  from  zero 
to  a  maximum  that  may  end  in  the  loss  of  consciousness. 
The  relation  to  the  intensity  of  stimulus  has  been  ex- 
pressed by  Wundt  in  a  curve  that  holds  for  stimuli  of 
certain  kinds,  although  there  may  be  exceptions.     A  faint 


FEELING  AND    AFFECTION  455 

Stimulus  is  usually  indifferent.  As  the  intensity  increases, 
a  pleasant  affection  begins  and  increases  to  a  maximum 
with  moderate  excitations,  and  then  drops  to  indifference, 
and  finally  becomes  unpleasant  as  the  excitation  is  in- 
creased still  more.  Where  pleasantness  disappears  varies 
with  the  nature  of  the  stimulus.  In  many  cases  it  is  at  a 
very  lowpoint  in  the  scale  of  intensities;  for  other  qualities 
all  but  the  highest  intensities  are  pleasant.  With  suit- 
able allowances,  practically  all  sense  quaHties  will  be  found 
to  correspond  with  the  rule  in  some  degree.  It  at  least 
approximates  a  law.  In  the  diagram  the  line  a  indicates 
the  increase  in  sensation  by  the  logarithmic  curve  in 
accordance  with  Weber's  law ;  e,  the  curve  of  increase  in 
intensity  of  affection,  above  the  Hne  indicating  pleasant, 
below  the  line  unpleasant  affection.  The  duration  of 
affection  varies  from  the  duration  of  the  stimulus  both 
at  the  beginning  and  the  end.  Affection,  as  was  said 
above,  lags  behind  the  stimulus,  appears  later,  a  little 
after  the  sensation  even,  in  most  cases,  and  may  either 
disappear  before  the  stimulus  or  change  its  tone  as  the 
stimulus  persists.  Thus,  stimuH  which  at  first  are  pleas- 
ant may  become  indifferent  or  become  unpleasant  if 
they  last  too  long.  Duration  has  much  the  same  ten- 
dency as  intensity  in  this  respect,  and  one  might  draw  a 
similar  curv-e.  The  tendency  is  always  for  the  feeling 
to  become  unpleasant  rather  than  pleasant  as  its  duration 
increases.  No  general  rule  can  be  given  even  for  the  same 
stimulus  as  to  how  great  the  duration  must  be  before 
the  quahty  will  change. 

Other    Suggested   Pairs    of   Feelings.  —  Wundt   and 
Royce  assert  that  there  are  other  definite  opposites  of 


456  FUNDAMENTALS    OF   PSYCHOLOGY 

consciousness  that  must  also  be  classed  as  feelings. 
Royce  adds  two,  restlessness  and  quiescence.  The  one 
is  said  to  be  characterized  by  a  constantly  changing  im- 
pulse to  movement,  particularly  by  a  feehng  that  one 
must  get  on  to  do  something  else ;  while  quiescence 
impHes  an  assent  to  the  present  condition,  a  readiness  to 
remain  in  the  condition  in  which  one  is.  Wundt  affirms 
that  there  are  three  pairs  of  affection  which  may  be 
regarded  as  constituting  a  three-dimensional  series.  To 
pleasantness-unpleasantness  he  adds  strain  and  relaxa- 
tion, excitation  and  quiescence.  Strain  and  relaxation 
are  related  to  the  feeling  of  effort  and  its  lack  in  attention, 
—  strain  appears  in  expectation,  relaxation  in  realiza- 
tion. Wundt  insists  that  these  qualities  do  not  come 
from  the  contraction  of  the  muscles  and  their  relaxation, 
but  are  as  truly  affections  without  assignable  sense  or- 
gans as  are  pleasantness  and  unpleasantness.  Excitation 
arises  when  one  is  disturbed  through  attempting  a  diffi- 
cult task,  is  a  component  of  anger  and  of  certain  exliila- 
rating  forms  of  joy.  Quiescence  or  inhibition  is  an 
accompaniment  of  rest,  perhaps  of  lassitude.  They,  too, 
are  peculiar  quaHties  of  affection  with  no  sense  organs  and 
no  definite  relations  to  the  other  forms  of  feeling.  These 
extra  pairs  were  supposed  to  be  accompanied  by  special 
physical  reactions,  but  later  investigators  seem  to  have 
pretty  clear  evidence  that  the  experiments  in  support  of 
them  were  inaccurate  or  wrongly  interpreted.  On  the 
whole,  direct  observation  seems  not  to  bear  out  Wundt's 
contention  that  these  forms  of  consciousness  are  feelings. 
There  can  be  no  doubt  that  the  states  exist,  but  they  seem 
to  be  either  directly  due  to  special  sensations  such  as  the 


FEELING   AND   AFFECTION  457 

kinaesthetic  impressions,  in  strain  and  relaxation,  or  to 
more  complicated  organic  processes  in  excitation  and 
quiescence.  These  are  probably  closely  related  to  the 
qualities  of  the  emotional  states  to  be  discussed  in  the 
next  chapter.  In  any  case  they  are  not  affections  in  the 
same  sense  as  are  pleasantness  and  unpleasantness. 

Affection  and  the  Qualities  of  Sensation.  —  It  would 
be  highly  desirable,  were  it  possible,  to  give  either  a 
catalogue  or  some  general  law  that  should  classify  the 
objects  or  stimuH  that  give  rise  to  pleasure  or  displeasure. 
We  have  already  attempted  this  for  the  intensity  and 
duration  of  stimuli.  To  list  the  quahties  that  are  pleas- 
ant is  much  more  difficult.  Experimental  aesthetics  has 
made  the  attempt  in  certain  fields,  but  the  results  are 
too  voluminous  to  be  presented  in  detail  and  the  general 
summaries  are  too  few  and  too  schematic  to  be  very 
satisfactory. 

Bodily  Accompaniments  of  Feeling.  —  WTiile  one 
becomes  acquainted  with  feehng  primarily  through  inner 
observation  or  introspection,  numerous  attempts  have 
been  made  to  obtain  some  record  of  the  behavior  in  feel- 
ing that  may  serve  as  a  measure  of  the  amount  of  feeHng, 
or  even  as  an  indication  of  the  nature  of  feeling.  It  is  a 
matter  of  common  observation  that  practically  all  indi- 
\'iduals  show  pleasure  or  displeasure  by  certain  physical 
changes.  The  face  is  said  to  light  up  or  to  lower  and  the 
general  bodily  attitude  changes  in  accordance  with  the 
feelings.  In  most  cases  the  presence  of  pleasure  or  its 
opposite  can  be  readily  and  clearly  detected  by  observa- 
tion. Many  investigations  have  been  undertaken  and 
carried  out  to  translate  these  simple  observations  into 


458  FUNDAMENTALS    OF    PSYCHOLOGY 

more  accurate  measurements.  One  of  the  first  series  of 
studies  was  of  the  changes  in  respiration  and_circulation. 
The  first  results  seemed  to  indicate  that  there  was  a  defi- 
nite opposition  in  these  processes  corresponding  to  the 
opposition  between  pleasantness  and  unpleasantness. 
Thus  Lehmann  ^  asserts  that  in  pleasure  respiration  is 
slow  and  deep,  while  in  unpleasantness,  at  least  after 
an  initial  inhibition,  it  is  quick  and  shallow.  The  pulse, 
similarly,  is  said  to  be  slow  and  strong  in  pleasure,  and 
quick  and  weak  in  unpleasantness ;  the  blood  vessels 
dilate  in  pleasure,  contract  in  unpleasantness.  Later 
investigations  by  Courtier,  Shepard,  and  others  make  it 
pretty  clear  that  the  effects  depend  very  largely  upon 
the  strength  of  the  stimuli  rather  than  upon  the  affective 
tone ;  that  all  stimuli  tend  to  quicken  the  respiration  and 
make  it  shallow,  to  quicken  the  pulse  and  make  it  feeble 
and  to  constrict  the  blood  vessels.  It  is  altogether  prob- 
able that  Lehmann's  results  with  pleasure  were  due  to  the 
fact  that  pleasant  stimuli  are  usually  faint,  and  so  if  there 
has  been  strong  stimulation  just  before,  the  vital  pro- 
cesses tend  to  return  to  normal  and  thus  seem  to  show 
changes  that  are  the  reverse  of  the  effects  of  the  stimula- 
tion. Wundt  and  his  students  have  attempted  to 
demonstrate  pecuHar  physiological  changes  of  the  same 
sort  in  connection  with  his  suggested  pairs  of  strain  and 
relaxation,  exaltation  and  depression ;  but  study  of  their 
curves  indicates  that  they  have  been  misled  by  similar 
phenomena  of  recovery,  and  by  rhythmic  changes  that 
have  no  relation  to  the  changes  in  the  feeling  that  they  are 
studying. 

^  Hauptgesetze  d.  menschlichen  Gefiihlsleben. 


FEELING  AND   AFFECTION  459 

Of  the  other  physiological  changes  in  connection  w^th 
feehng,  the  secretion  of  saliva  has  been  studied  most 
extensively  by  Pawlow.  He  found  that  it  was  possible 
to  record  many  of  the  changes  both  in  feehngs  and  in  the 
intellectual  processes  of  the  dog  by  measuring  the  flow 
of  saHva.  This  he  accomplished  by  dissecting  out  the 
duct  of  the  salivary  gland  in  the  cheek  of  the  dog,  and 
adjusting  it  so  that  the  saHva  might  flow  into  the  pan  of 
a  recording  scale.  It  was  found  that  the  sight  of  food  or 
of  any  object  associated  with  food  led  to  an  increased 
flow,  and  that  the  amount  secreted  was  a  very  good  indi- 
cation of  the  mental  state  of  the  dog.  This  corre- 
sponds to  the  dryness  of  the  mouth  in  man  in  displeasure 
or  excitement,  particularly  in  fear,  and  the  free  flow  of 
saliva  in  pleasure  even  when  that  be  not  associated  with 
food.  The  opposition  between  pleasantness  and  un- 
pleasantness does  not  hold  altogether  here,  again,  since 
any  strong  excitement,  pleasant  or  unpleasant,  gives  the 
same  dry  mouth.  Somewhat  the  same  statement  may  be 
made  of  the  secretion  of  tears.  Strong  grief  or  displeas- 
ure causes  weeping,  but  the  brightness  of  the  eye  in 
pleasure  is  also  due  to  increased  secretion  of  the  lachrymal 
gland  which  in  extreme  pleasure  may  overtax  the  tear 
ducts  and  flow  dow^n  the  cheek.  SHghtly  better  evidence 
may  be  given  for  an  opposition  in  expression  in  the 
bodily  posture.  Grief  seems  to  be  marked  by  a  drawing 
together  of  all  the  members,  while  pleasure  leads  to  an 
actual  physical  expansion,  —  head  erect,  even  thrown 
back  as  in  laughter,  the  arms  extended  and  the  trunk  held 
straight.  These  general  bodily  movements  have  been 
much  less  carefully  studied  than  the  others,  and   the 


460  FUNDAMENTALS    OF    PSYCHOLOGY 

opposition  of  the  different  kinds  of  feelings  shown  in 
superficial  observations  may  disappear  when  the  subject 
is  studied  more  closely.  We  may  assert,  then,  that  the 
feelings  show  very  marked  bodily  accompaniments,  but 
that  these  cannot  be  said  to  correspond  accurately  to  the 
differences  between  pleasantness  and  unpleasantness, 
although  the  degree  of  our  feeling  carries  with  it  an 
approximately  corresponding  amount  or  intensity  in  the 
accompanying  physical  expression.  The  expression  of 
the  feelings  merges  gradually  into  emotional  expression, 
which  must  form  a  considerable  portion  of  the  matter 
of  the  next  chapter. 

Theories  of  Feeling.  —  In  attempting  to  summarize 
the  facts  collected  concerning  feeling  and  to  refer  them  to 
a  single  principle,  many  theories  have  been  developed. 
At  present  the  facts  cannot  be  brought  to  harmonize 
with  any  single  general  statement,  but,  rather,  different 
groups  of  facts  may  be  brought  to  the  support  of  differ- 
ent statements  in  themselves  not  altogether  consistent. 
While  no  single  theory  may  be  said  to  be  true  to  the  ex- 
clusion of  the  others,  all  taken  together  give  a  better  idea 
of  the  nature  of  feeling  and  its  relations  than  can  be  ob- 
tained by  any  mere  statement  of  facts.  The  first  ele- 
ment that  is  lacking  in  the  construction  of  a  theory  is  a 
satisfactory  basis  in  the  nervous  system.  Each  of  the 
other  fundamental  processes  has  a  definite  nervous 
structure  or  activity  to  which  it  may  be  referred  and 
which  gives  definiteness  to  the  explanation,  but  affection 
has  neither  special  sensory  nerves  to  provide  it  a  particu- 
lar stimulus,  nor  special  central  structures  that  elaborate 
its  materials.     Study  of  pathological  cases  of  disturbances 


FEELING   AND    AFFECTION  46 1 

of  the  affective  life,  such  as  those  that  show  symptoms  of 
melanchoha  or  euphoria,  are  accompanied,  so  far  as  at 
present  knowTi,  by  no  pecuHar  lesions  with  which  the 
diseased  affections  may  be  associated  or  to  which  they 
may  be  referred.  So  far  as  changes  in  the  nerve  tissue 
have  been  traced,  they  are  widespread  and  general  rather 
than  closely  localized  and  specific.  It  cannot  be  said 
that  one  is  pleased  or  displeased  in  any  particular  part 
of  the  brain  or  nervous  system,  or  that  affection  is  carried 
by  any  particular  nerve  or  corresponds  to  any  pecuhar 
process. 

Physiological  Theories.  —  Of  the  theories,  we  may  dis- 
tinguish three  main  groups  ^^'ith  several  cross  hnes  of 
di\'ision.  One  of  the  oldest  and  most  generally  accepted 
makes  pleasure  and  displeasure  the  accompaniment  and 
indication  of  benefit  and  injury  to  the  organism.  This 
takes  different  forms,  either  as  an  expression  of  an  imme- 
diate change  in  the  organism  in  general,  of  the  nervous 
system  as  a  whole,  or  of  some  particular  part  of  the  nervous 
system.  It  may  be  an  indication  of  what  has  been  good 
or  bad  for  the  individual  or  race  in  the  past  and  is  Hkely 
to  prove  so  in  the  future.  For  these  theories,  pleasure 
means  that  there  is  going  on  in  the  individual  at  the 
moment  a  process  of  upbuilding,  of  anaboKsm  ;  that  this 
anaboHsm  is  induced  in  the  nervous  system  as  a  whole  or 
is  going  on  in  the  frontal  lobe,  for  Wundt  the  great 
coordinating  centre  for  all  nervous  and  mental  activity. 
The  evidence  for  each  of  these  theories  is  indirect  and  may 
be  found  in  the  general  law  that  the  beneficial  is  on  the 
whole  pleasant,  that  the  injurious  is  on  the  whole  un- 
pleasant.    Correspondingly,  when  one  is  physically  in 


462  FUNDAMENTALS    OF   PSYCHOLOGY 

good  health,  well  rested  and  nourished,  many  activities 
and  even  excitations  are  pleasant  that  become  unpleasant 
when  the  physical  tone  is  lower.  These  facts  have  been 
interpreted  to  mean  that  action  of  a  well-nourished  ner- 
vous system  or  part  of  the  nervous  system  means  pleas- 
ure, of  a  badly  nourished  means  displeasure.  Taken 
literally,  the  identification  of  pleasure  with  anaboHsm^ 
and  displeasure  with  catabolism,  would  make  all  action 
and  stimulation  unpleasant,  since  all  action  involves  use 
of  reserve  nutriment.  The  anabolism-catabolism  for- 
mula has  been  modified  by  permitting  catabolism  within 
moderate  limits,  the  limits  of  ready  recuperation,  to  give 
pleasure.  This  point  would  be  difficult  to  determine 
empirically,  however. 

Another  change  in  the  statement  of  the  theory  per- 
mits the  formula  to  mean  a  general  benefit  or  injury  to 
the  race  in  the  evolutionary  sense.  This  enables  one  to 
account  for  many  of  the  seeming  discrepancies  between 
benefit  and  pleasure.  Thus,  it  seems  at  first  not  true, 
even  in  general,  that  the  pleasant  in  food  or  drink  is  also 
beneficial.  Aside  from  exceptions  we  do  use  feeling  as  a 
guide  to  foods.  We  eat  what  we  like,  or  at  least  we  do 
not  eat  what  we  do  not  like.  The  exceptions  apply  to 
excesses  or  to  substances  of  rare  occurrence  in  the  environ- 
ment in  which  the  race  evolved.  The  race  as  a  whole 
is  more  likely  to  survive  if  it  makes  use  of  pleasant  but 
injurious  foods,  such  as  sweet  poisons,  than  if  it  ate  no 
sweets.  The  exceptions  must  be  learned  by  individual 
experience.  It  is  much  better  to  eat  than  not  to  eat,  in 
spite  of  the  fact  that  overeating  is  harmful.  When  to 
stop  can  be  learned  from  the  unpleasant  symptoms  that 


FEELING  AND   AFFECTION  463 

indicate  injury.  Pleasantness  and  unpleasantness  serve 
as  a  general  guide  to  conduct,  and  may  be  said,  meta- 
phorically, to  be  the  expression  in  the  individual  of  the 
experience  of  the  race  as  to  what  is  good  or  bad.  This 
expression  is  open  to  many  exceptions,  is  not  a  final  law, 
but  must  be  modified  by  the  experience  of  the  indi\'idual 
and  the  accumulated  knowledge  of  the  race.  It  should 
be  added  that  how  the  experience  is  recorded  and  trans- 
mitted in  the  individual  and  how  and  why  it  acts  are  not 
at  all  known.  The  theory  is  nothing  more  than  a  formula- 
tion of  the  general  group  of  facts  that,  in  the  long  run, 
what  pleases,  benefits  ;   what  displeases,  harms. 

Furtherance-Hindrance  Theories.  —  A  second  group 
of  theories  accounts  for  the  more  active  pleasures  largely 
overlooked  in  the  theories  just  mentioned.  This  group 
couples  easy  running  or  unopposed  action  with  pleasure, 
difficult  or  opposed  action  with  displeasure.  In  one 
form  the  theory  makes  real  physical  movements  the  basis, 
in  other  groups  it  is  taken  in  a  more  metaphorical  sense. 
Thus,  the  first  theory  states  that  a  smooth,  graceful  curve 
is  pleasant  because  the  eye  will  follow  it  without  effort, 
with  a  single  sweep ;  while  a  series  of  short  lines  with 
many  changes  in  direction  is  ugly  because  of  the  difficulty 
of  the  eyes  in  following  them.  A  sKght  departure  toward 
the  metaphorical  is  seen  in  the  theory  of  '  empathy ' 
(Einfiihlung)  of  Lipps,  in  which  the  individual  does  not 
necessarily  have  opposed  action  in  his  own  body,  but  sym- 
pathizes with  the  figure,  feels  in  unpleasantness  that  he 
would  have  difficulty  in  doing  what  he  personifies  the 
figure  as  doing.  Finally,  we  have  Stout's  theory  that  one 
may  have  opposition  in  the  accomplishment  of  an  intel- 


464  FUNDAMENTALS    OF   PSYCHOLOGY 

lectual  purpose,  in  reaching  some  conclusion  in  thought ; 
or,  on  the  contrary,  one's  mental  operations  may  run 
smoothly  or  be  helped,  and  so  be  pleasant.  In  each  of 
these  cases  furtherance  or  easy  action  means  pleasure, 
hindrance  or  interrupted  action  displeasure.  As  before, 
one  may  accept  the  general  statement,  particularly  in 
the  metaphorical  form,  although  the  more  specific  appli- 
cations offer  much  room  for  doubt  and  may  be  disputed 
as  to  facts. 

Feelings  Dependent  upon  Earlier  Experiences.  — 
The  third  form  of  theory  attempts  an  explanation  of  how 
feeling  can  be  dependent  upon  such  a  wide  range  of  expe- 
riences, rather  than  why  one  is  pleased  or  displeased. 
The  first  form  of  this  theory  is  Wundt's  statement  that 
feeling  is  the  obverse  of,  or  at  least  one  phase  of,  appercep- 
tion. For  Wundt,  apperception  is  practically  synony- 
mous with  the  active  fife,  covers  much  of  what  is  treated 
under  attention,  perception,  and  will.  It  is  the  effect 
of  the  entire  earher  experience  of  the  individual  in  the 
control  of  his  present  action  in  attending,  in  interpreting 
the  material  offered  to  perception,  in  thought,  and  in 
practical  conduct.  This  definition  makes  feeling  an 
expression  of  the  interaction  between  the  coordinated 
earlier  experience  of  the  individual  and  the  present 
experience.  On  the  nervous  side,  Wundt  gives  apper- 
ception a  seat  in  the  frontal  lobe,  probably  in  the  front 
portion  of  the  frontal  lobe,  and  so  combines  his  psycholog- 
ical theory  with  the  physiological  in  the  formula  men- 
tioned above,  that  pleasure  corresponds  to  the  action  of  a 
well  nourished,  displeasure  to  the  action  of  a  badly  nour- 
ished, frontal  lobe.     This  means  or  may  be  made  to  mean 


FEELING   AND   AFFECTION  465 

that  whether  any  process  is  pleasant  or  unpleasant 
depends  upon  the  entire  accumulated  experience  of  the 
indi\'idual  and  in  the  way  that  experience  is  brought  to 
bear  upon  the  process  in  question,  a  statement  that  is 
undoubtedly  true,  although  somewhat  vague.  If  we 
replace  apperception  by  attention,  and  consider  the 
nervous  factors  that  are  found  to  play  a  part  in  the  con- 
trol of  attention,  we  would  have  approximately  the  same 
formula  in  our  own  terms. 

We  may  assert  that  feeHng  is  an  expression  of  the 
factors  that  control  attention,  an  expression  of  the  inter- 
action between  the  instincts  and  past  experience  of  the 
individual,  and  the  present  situation ;  an  expression  of 
the  reaction  of  the  nervous  system  of  the  individual,  as 
the  result  of  original  endowment  and  individual  acquire- 
ment, to  the  stimuH  of  the  moment.  To  give  an  explana- 
tion of  pleasantness  and  unpleasantness  this  formula 
would  need  to  consider  the  essential  phases  of  the 
other  two  theories.  The  theories  are  mutually  com- 
plementary rather  than  exclusive.  Thus,  the  peculiar 
reaction  that  gives  rise  to  pleasure  is  an  indication  that 
the  stimulus  in  question  has  been  beneficial ;  those  that 
give  rise  to  displeasure  have  been  on  the  whole  injurious, 
either  to  the  race  or  to  the  individual.  In  the  one  case 
we  deal  with  an  instinctive  response,  in  the  other  with 
a  response  due  to  individual  acquirement.  In  the  in- 
dividual acquirement,  association  with  similar  expe- 
riences or  direct  connection  with  other  experiences,  either 
in  themselves  unpleasant  or  pleasant,  plays  a  large  part. 
One  may  get  the  affection  of  the  associated  experience 
without  having  that  definitely  recalled,  as  can  be  seen 


466  FUNDAMENTALS    OF    PSYCHOLOGY 

in  the  dislike  of  many  foods  with  which  one  has  had  un- 
pleasant experiences, -or  a  liking  for  colors  that  have  been 
connected  with  some  very  pleasant  occasion.  The  feehng 
comes  here  without  necessarily  recalHng  the  event  that 
may  reasonably  be  supposed  to  have  occasioned  it. 
Just  what  the  nature  of  the  reaction  may  be  that  gives 
rise  to  feeling,  why  we  become  conscious  in  feeling  of  the 
nature  of  the  forces  that  are  active  in  controlHng  atten- 
tion, we  cannot  at  present  say.  The  justification  for  the 
theory  is  the  far-reaching  dependence  of  feelings  upon  so 
much  of  the  earher  life  of  the  individual. 

REFERENCES 

TiTCHENER :   Psychology  of  Feeling  and  Attention. 
Marshall  :  Pain,  Pleasure,  and  ^Esthetics. 


CHAPTER  XIV 

EMOTION  AND   TEMPERAMENT 

Probably  the  most  impelling  and  self-asserting  mental 
state  in  all  of  the  Kst  is  emotion.  For  good  or  for  ill  it 
marks  the  greatest  disturbance  in  the  course  of  mental 
events  and  is  the  most  personal,  the  most  pervasive. 
Emotions  stand  in  closest  connection  with  feeling  and 
with  instinct.  From  the  feelings  they  can  be  distin- 
guished only  by  the  amount  of  response  that  accompanies 
them  and  by  their  general  complexity.  Unpleasantness 
becomes  anger  or  fear  when  movements  of  attack  or 
flight  begin,  when  the  muscles  of  the  face  and  of  the 
internal  organs  grow  tense  and  give  rise  to  sensations. 
On  the  other  hand,  many  of  the  occasions  for  the  emo- 
tions and  practically  all  of  the  movements  accompany- 
ing emotion  are  instinctive.  Emotion  may  be  defined 
by  \irtue  of  these  relationships  either  as  a  complicated 
feeHng  or  the  subjective  side  of  the  instinct.  The  list 
of  emotions  ordinarily  given  has  varied  relatively  little 
since  Descartes,  and  his  list  can  be  traced  with  compara- 
tively few  changes  to  much  earlier  periods.  His  list  in- 
cludes surprise,  love  and  hate,  desire,  pleasure  and  dis- 
pleasure ;  while  in  Shand,  one  of  the  latest  writers  who 
has  elaborated  upon  the  classification,  we  find  fear, 
anger,  joy,  sorrow,  disgust,  wonder,  to  which  McDougall 

467 


468  FUNDAMENTALS   OF  PSYCHOLOGY 

adds  the  more  personal  qualities  of  dejection  and  elation. 
These  are  for  all  authorities  the  more  fundamental  emo- 
tions. The  others  develop  from  them  by  combination, 
by  change  in  intensity,  in  the  nature  of  the  object  that 
arouses  them,  or  in  the  time  at  which  the  event  that 
arouses  the  emotion  has  occurred  or  is  to  occur. 

Classifications  of  the  Emotions.  —  In  any  discussion 
of  the  emotions  it  is  essential  to  consider  separately  two 
factors,  the  conditions  or  causes  of  the  emotions  and  the 
mental  content  and  physical  reaction  during  the  emo- 
tion. There  are  two  possible  classifications  of  emotions 
with  reference  to  cause,  although  the  cause  does  not 
necessarily  affect  the  quality  of '  the  emotions.  Two 
general  causes  for  emotions  have  been  assigned.  One, 
generally  current  at  present,  asserts  that  emotion  is 
merely  an  instinct  seen  from  the  inside,  that  the  real 
cause  is  to  be  found  in  the  instinctive  response.  The 
other,  which  goes  back  to  remote  antiquity,  insists  that 
emotions  arise  from  some  conflict  between  ideals  or 
desires  and  the  momentary  environment.  The  first 
theory  applies  best  to  those  emotions  called  out  imme- 
diately by  some  external  stimulus  by  virtue  of  a  funda- 
mental characteristic  of  the  organism..  Sudden  fear 
at  sight  of  a  snake,  sudden  anger  at  an  injury,  the  sudden 
glow  of  love  at  first  sight,  all  fall  in  this  class.  They 
need  no  explanation  other  than  the  inherited  nervous 
mechanism. 

The  second  group  of  theories  finds' its  explanation  in 
the  checking  of  some  general  movement  or  current  in 
the  life  of  the  individual.  In  the  writings  of  the  older 
men  one  finds  much  difference  of  opinion  as  to  what  it 


EMOTION  AND   TEMPERAMENT  469 

was  that  moved,  but  they  agree  that  all  emotions  arise 
from  a  checking  or  facilitation  of  the  movement,  and 
also  that  unpleasant  emotions  arise  from  the  checking, 
pleasant  emotions  from  the  faciUtation.  For  Descartes 
the  obstruction  was  suffered  by  the  movements  of  the 
fluid  products  of  digestion  or  the  blood ;  for  Spinoza  the 
movement  was  of  an  unnamed  mental  force  which  was 
pressing  towards  a  goal  of  hypothetical  perfection. 
For  Shand  the  impelHng  force  is  what  he  calls  sentiment, 
a  force  derived  in  part  from  instinct,  in  part  from 
experience,  and  in  part,  perhaps,  underived,  which  ex- 
hibits systems  or  groups  of  forces  in  ever-widening  sub- 
ordinations. These  he  di\ddes  into  the  three  classes : 
love,  parental  sentiment,  and  the  unselfish  or  social 
sentiment.  When  these  sentiments  find  free  play  or 
are  assisted,  pleasant  emotions  are  experienced;  when 
checked  or  thwarted  in  any  way  the  emotion  is  unpleas- 
ant. ''  Every  primary  impulse  .  .  .  when  opposed 
tends  to  arouse  anger ;  when  satisfied,  joy ;  when  frus- 
trated, sorrow;  and  when  it  anticipates  frustration, 
fear." 

The  System  of  Purposes  in  Emotion.  —  If  one  is  to 
accept  at  all  this  old  theory,  obviously  the  first  problem 
is  to  determine  what  it  is  that  gives  rise  to  the  deter- 
mining impulse  or  sentiment,  or,  in  a  more  conscious 
sense,  the  goal  of  action.  As  was  seen  in  an  earlier 
chapter,  instinct  suppKes  the  impelKng  force,  the  direct- 
ing influence  in  most  conscious  processes.  To  it  are  due 
the  fundamental  tendencies.  But  upon  them  is  built 
a  great  superstructure  of  desires,  acquired  from  edu- 
cation, through  living  in  a  particular  environment,  that 


47©  I'UKDAMENTALS   OF   PSYCHOLOGY 

serves  to  differentiate  the  aims  of  the  individual  from 
his  fellows,  and  that  characterizes  the  ideals  of  the  people 
of  one  community  or  social  stratum  or  of  one  country  or 
of  one  race.  The  last  two  mentioned  are  dependent  in 
part  upon  social  instincts  that  make  the  suggestions 
and  the  aims  of  the  group  acceptable  to  the  individual. 
The  traits  common  to  all  are  instinctive ;  the  more  par- 
ticular result  from  education.  Granted  that  it  is  instinc- 
tive to  attain  wealth,  one  must  admit  that  the  form  that 
wealth  is  to  take  varies  from  race  to  race,  and  the  amount 
aimed  at  is  different  for  different  social  groups  within 
the  community.  Whether  one  strives  for  the  wampum 
or  cattle  of  the  savage,  as  opposed  to  the  bank  account 
of  modern  man,  is  a  question  of  environment,  as  is 
whether  one  sets  one's  goal  at  millions  or  thousands. 
Similarly,  desire  for  social  approval,  for  what  may  be 
called  fame,  is  general,  perhaps  instinctive,  but  whether 
in  athletic  skill  or  scholarship,  whether  in  business  or  in 
art,  in  politics  or  war,  depends  upon  early  environment 
and  even  upon  chance  factors  in  education.  Both  the 
sentiments  and  impulses  of  instinctive  origin  and  the 
ambitions  developed  at  the  more  conscious  stage  must 
be  assumed  if  emotion  is  to  exist.  An  individual  to 
whom  nothing  really  mattered  would  be  without  emotion. 
The  presence  of  a  system  of  aims  makes  possible  the 
bare  potentiality  of  emotion ;  the  nature  of  the  aim 
determines  the  character  of  the  objects  that  shall  excite 
the  emotions.  The  emotion  itself  is  an  incident  in  the 
struggle  for  the  attainment  of  an  end. 

The    Qualities   of   Emotion.  —  While   one   may   dis- 
tinguish two  classes  of  emotion  from  the  standpoint  of 


EMOTION   AND    TEMPEILA.MENT  47 1 

their  conditions,  no  corresponding  difference  can  be 
discovered  in  the  qualities  of  emotion.  From  compar- 
ing the  qualities  of  the  results,  it  is  impossible  to  say 
whether  anger  has  been  produced  by  a  sudden  swift 
reaction  to  an  act  of  brutahty  towards  yourself  or  an- 
other, or  whether  it  is  the  result  of  being  thwarted  in 
a  long-cherished  ambition.  The  exultation  over  obtain- 
ing the  means  of  satisf}dng  a  long-continued  hunger  is 
no  different  from  the  exultation  over  winning  an  aca- 
demic honor.  No  distinction  in  quahty  can  be  made 
between  emotions,  however  different  may  be  their  con- 
ditions or  origin.  We  must  turn  now  to  consider  the 
qualities  of  emotions  and  to  determine  upon  what  the 
quahties  depend. 

Recent  discussion  has  revolved  more  about  the 
qualities  of  the  emotion  than  the  occasions.  In  its 
descriptions  and  explanations  it  savors  much  of  ancient 
theories.  These  had  much  to  say  about  the  part  of  the 
body  that  was  active  in  the  emotion  and  were  very  full 
in  their  descriptions  of  the  accompanying  physical 
states.  Thus,  Plato  assigned  courage,  ambition,  and 
the  nobler  emotions  to  the  heart,  while  lust  and  the 
baser  passions  had  their  seat  below  the  diaphragm. 
In  common  observation  one  may  find  the  explanation  of 
these  references  in  the  sensations  derived  from  the  gen- 
eral region  of  the  body  in  which  the  movements  are 
felt.  The  changes  in  rate  of  breathing,  in  the  circula- 
tion, contractions  of  the  muscles  of  the  chest  and  abdo- 
men, all  are  noted  by  the  chance  observer  and  play  a 
large  part  in  the  novehst's  descriptions  of  mental  states. 
While  the  modern  author  no  longer  ascribes  the  emo- 


472  FUNDAMENTALS    OF   PSYCHOLOGY 

tions  to  the  internal  organs  in  the  same  sense  as  did 
the  ancients,  he  still  looks  to  the  organic  sensations  for 
the  coloring  of  his  emotions ;  in  fact,  for  a  quarter  of  a 
century  psychologists  have  been  engaged  in  a  contro- 
versy as  to  whether  these  organic  changes  did  not  con- 
stitute both  the  origin  and  the  content  of  emotion. 

James-Lange  Theory.  —  This  controversy  began  with 
and  has  revolved  about  a  theory  propounded  simul- 
taneously by  Lange  and  James.  The  theory,  put 
briefly,  is  that  the  movements  of  the  body  when  felt 
are  the  emotion,  and  that  the  mental  factors  are  alto- 
gether subordinate.  James  states  it  in  the  apparent 
paradox  that  you  are  sad  because  you  weep  rather  than 
weep  because  you  are  sad.  He  enumerates  a  number 
of  cases  in  which  the  emotion  comes  only  after  the 
movements  have  been  felt.  One  may  face  a  situation 
with  no  great  appreciation  of  its  danger,  even  with 
knowledge  that  it  is  not  dangerous,  and  suddenly  be- 
come aware  of  a  trembling,  together  with  a  sinking 
feeling  in  the  abdomen ;  with  this  the  emotion  of  fear  is 
fully  established.  One  may  look  over  a  cliff  with  per- 
fect confidence  of  safety,  and  then  suddenly  have  a  dizzi- 
ness and  trembhng  come  on  that  destroys  one's  self- 
assurance  and  even  compels  one  to  draw  back  involun- 
tarily. In  these  cases  action  and  thought  seem  to  be  at 
variance,  and  action  takes  precedence  over  thought. 
The  theory  in  general  must  be  accepted  as  at  least  a 
rough  statement  of  certain  facts,  and  this  makes  it  nec- 
essary to  examine  carefully  the  opposing  arguments. 

Obviously  the  problem  revolves  about  the  possibil- 
ity of  discovering  instances  in  which  emotions  disappear 


EMOTION   AND   TEMPERAMENT  473 

with  loss  of  organic  sensations,  and  instances  in  which 
the  bodily  reactions  occur  and  give  rise  to  emotion 
when  the  ordinary  conditions  of  emotion  are  absent. 
The  first  condition  was  fulfilled  by  certain  hysterical 
patients  who  were  completely  anaesthetic  in  both  inter- 
nal organs  and  external  muscles.  Several  of  these 
were  questioned  in  the  interests  of  the  theory.  The 
reports  agree  in  general  that  complete  anaesthesia  in 
the  parts  usually  involved  in  the  emotions  is  accom- 
panied by  loss  of  emotion.  One  patient,  a  man  who  had 
always  been  normally  emotional,  suddenly  lost  all  sen- 
sitiiity  and  immediately  thereafter  became  absolutely 
indifferent  to  all  that  passed  about  him.  He  parted 
from  his  wife,  of  whom  he  was  very  fond,  without  any 
feeling  of  sorrow,  and  his  reactions  to  experiences  that 
had  pre\dously  been  strongly  toned  suddenly  became 
neutral  or  were  lacking  altogether.  While  the  fact  is 
generally  accepted,  Solher  ^  has  questioned  whether  the 
loss  of  emotion  is  due  to  the  disappearance  of  sensation 
or  to  the  general  reduction  in  the  cortical  tone  in  hys- 
teria. Hysterical  patients  also  suft'er  diminution  of  all 
the  higher  psychical  functions,  so  that  it  is  not  at  all 
surprising  that  their  abiHty  to  appreciate  the  experi- 
ence in  a  way  to  arouse  emotions  should  be  lost.  In 
this  case  the  failure  to  have  emotions  would  be  due  to 
the  intellectual  defects  or  to  defects  in  the  higher 
cortical  centres  rather  than  to  the  mere  failure  to  feel 
responses. 

Almost  as  contradictory  results  were  obtained  from 
a  study  of  actors  who  were  questioned  on  the  supposi- 

1  Le  mecanisme  des  emotions. 


474  FUNDAMENTALS   OF   PSYCHOLOGY 

tion  that  they  would  pro\dde  instances  in  which  the 
emotion  would  be  felt  when  the  movements  were  made 
without  any  real  occasion  for  the  response.  A  number 
of  famous  actors  and  actresses  were  asked  whether  they 
felt  the  emotions  that  they  depicted.  The  answers 
showed  that  they  were  divided  into  two  groups :  those 
who  really  felt  what  they  were  portraying,  and  a  second 
group  who  merely  carried  through  their  parts  as  ma- 
chines. Some  asserted  that  they  felt  after  a  perform- 
ance as  if  they  had  actually  experienced  the  events  of 
the  play  and  felt  during  the  performance  as  keenly  as  if 
the  scenes  were  real;  the  others  were  perfectly  cold. 
No  definite  division  could  be  made  between  the  groups 
on  the  basis  of  distinction  or  success ;  it  seems  merely 
that  one  group  conforms  to  the  demands  of  the  theory, 
the  other  does  not.  James  asserts  that  one  must 
assume  that  in  one  group  only  the  external  muscles,  the 
muscles  of  the  face  and  those  that  give  the  bodily  pos- 
tures, are  affected,  while  the  deeper-lying  reactions  are 
lacking.  It  would  seem  from  this  that  the  sensations 
essential  to  the  complete  emotional  experience  come 
from  the  acti\dty  of  the  internal  organs.  The  others 
are  at  least  less  important. 

In  any  discussion  of  this  theory  a  sharp  line  must  be 
drawn  between  the  condition  of  an  emotion  and  its  quali- 
ties. James  assumes  the  movements  and  raises  no  ques- 
tions as  to  how  they  are  excited.  He  takes  them  for 
granted  as  fundamental  reactions  of  the  nervous  system. 
He  is  content  in  his  detailed  discussion  to  show  that  the 
emotion  as  we  feel  it  is  nothing  more  than  the  awareness 
of  the  bodily  state  without  attempting  to  say  what  causes 


EMOTION   AND   TEMPERAMENT  475 

the  reaction  itself.  He  asks  only  whether  anything 
other  than  the  movements  can  contribute  to  the  emo- 
tional experience.  Granting  that  this  in  the  main 
must  be  answered  in  the  affirmative,  much  remains  to  be 
done. 

It  is  to  be  noted  in  James'  discussion  that  he  does  not 
specify  with  great  accuracy  what  the  movements  in  any 
particular  emotion  may  be.  He  is  content  to  assert 
that  there  are  movements  and  to  prove  that  these  con- 
stitute the  quality  of  the  emotion.  In  this  most  of  his 
disciples  have  followed  him.  They  speak  much  of 
strains,  sinking  feelings,  and  the  Hke,  but  no  single 
emotion  is  distinctly  described  and  distinguished  from 
others  on  the  basis  of  its  bodily  accompaniments.  For 
attempts  at  these  details  one  must  turn  to  recent  inves- 
tigations in  physiology. 

The  Sympathetic  System  in  Emotion.  —  Cannon  ^  and 
his  students  and  Sherrington  have  made  experiments 
which  show  what  some  of  the  changes  are  and  what 
part  they  play  in  the  emotion.  Cannon  asked  two  ques- 
tions :  I .  What  are  the  bodily  responses  in  fear,  anger, 
and  general  excitement?  and  2.  What  is  the  value  of 
these  responses  to  the  organism?  For  an  answer  to  the 
first  question  he  looked  to  demonstrable  organic  re- 
sponses. In  general,  emotions  were  found  to  spread 
through  the  sympathetic  system  to  practically  all 
of  the  abdominal  organs.  Pawlow  had  shown  that 
the  flow  of  saHva  and  the  secretion  of  the  digestive 
fluids  in  the  stomach  were  increased  by  the  taste  or  odor 
of  pleasant  foods,  even  by  sights  or  sounds  that  had 

1  Bodily  Changes  in  Pain,  Hunger,  Fear,  and  Rage. 


476  FUNDAMENTALS   OF   PSYCHOLOGY 

been  associated  with  such  foods.  It  has  also  been 
shown  that  pain  or  the  emotions  excited  in  a  dog  by 
the  sight  of  a  cat  or  in  a  cat  by  the  attempted  attack 
of  a  dog  served  to  check  the  flow  of  these  secretions  even 
when  food  was  taken  into  the  mouth.  These  emotions 
also  inhibited  the  movements  of  the  ahmentary  canal 
which  usually  serve  to  force  the  food  through  it.  Some 
of  the  effects  may  be  seen  in  man,  in  whom  vomiting 
reflexes  are  caused  at  times  by  exceptionally  strong 
emotions,  particularly  by  sorrow  and  fear,  not  to  men- 
tion the  slighter  reactions  always  present  in  disgust. 

The  Adrenal  Gland  in  Emotion.  —  Cannon's  experi- 
ments prove  definitely  the  importance  of  the  emotion 
upon  the  secretions  of  the  adrenal  gland,  a  small  gland 
above  the  kidneys.  This  gland  has  been  shown  to  be 
called  into  activity  by  stimulation  of  the  splanchnic 
nerve,  one  of  the  sympathetic  system.  The  gland  was 
also  shown  to  be  excited  in  most  of  the  violent  emotions, 
by  pain,  anger,  fear,  and  by  general  excitement.  The 
effects  of  this  secretion  are  widespread.  Briefly  enumer- 
ated, it  serves  first  to  contract  the  small  blood  vessels 
and  to  increase  the  ease  with  which  the  blood  will  clot. 
This  action  may  be  illustrated  by  the  use  made  of  it 
by  the  physicians  in  applying  adrenin,  the  substance 
obtained  from  the  adrenal  glands  of  animals,  to  stop 
superficial  bleeding.  A  second  action  of  the  glands  is 
to  increase  the  amount  of  glycogen  or  so-called  blood 
sugar  in  the  circulation.  This  seems  to  be  due  to  the 
action  of  the  adrenal  secretion  upon  the  liver,  causing 
it  to  release  its  stores  of  glycogen  and  pour  them  into 
the  blood,  whence  they  are  carried  to  the  parts  of  the 


EMOTION   AND    TEMPERAMENT  477 

body  that  may  need  them.  A  secondary  consequence 
of  these  actions  is  that  the  effects  of  fatigue  are  checked 
for  a  time,  and  the  muscles  respond  with  renewed 
strength.  This  is  due  in  part  to  the  fact  that  the  con- 
striction of  the  blood  vessels  increases  the  blood  pres- 
sure and  so  more  thoroughly  and  quickly  washes  out 
the  poisonous  products  of  earlier  action,  and  in  part 
to  the  fact  that  the  glycogen  furnishes  a  quickly  assim- 
ilated food  to  the  muscle.  It  could  be  demonstrated 
that  stimulation  of  the  adrenal  glands  produced  each  of 
these  effects,  the  blood  vessels  were  contracted,  the  blood 
pressure  increased  in  consequence,  the  composition  of 
the  blood  was  changed  so  that  it  coagulated  more  easily, 
the  liver  was  stimulated  to  secrete  its  sugar  and,  as  a 
result,  fatigued  muscles  were  temporarily  increased  in 
strength. 

These  same  effects  were  all  produced  by  pain  or 
strong  emotion,  pro\dded  the  adrenal  glands  were  pres- 
ent and  connected  with  the  sympathetic  system.  The 
increase  of  blood  pressure  in  emotion  is  well  known  and 
experiments  showed  that  the  blood  would  coagulate  more 
quickly  after  strong  emotion.  The  increase  in  the  sugar 
in  the  blood  was  demonstrated  in  cats  subjected  to  pain, 
or  that  had  been  frightened  by  dogs  when  no  injury 
could  be  done  them.  The  same  effect  is  exerted  in 
man.  It  was  found  that  of  twenty-five  players  on  a 
Harvard  football  squad  twelve  had  an  increased  secre- 
tion of  glycogen,  as  shown  by  sugar  in  the  urine,  after 
the  contest  was  over.  That  this  condition  was  in  part 
due  to  emotion  was  shown  by  the  fact  that  five  of  the 
twelve  were  substitutes  who  took  no  part  in  the  game 


478  FUNDAMENTALS    OF    PSYCHOLOGY 

and  that  the  only  excited  spectator  examined  also 
showed  the  same  reaction.  Students  examined  before 
and  after  a  difficult  and  important  examination  showed 
presence  of  glycogen  after,  but  not  before,  the  test. 

Looking  at  the  phenomenon  as  a  whole,  one  may  read- 
ily see  the  utility  of  these  reactions  in  emotions.  The 
strong  emotions,  particularly  the  unpleasant  emotions, 
are  in  animals,  and  were  in  primitive  man,  very  likely 
to  be  followed  by  a  fight  or  other  violent  effort.  The 
animal  subject  to  emotion  must  usually  either  fight  or 
run.  The  bodily  changes  are  a  preparation  for  this 
effort.  The  contraction  of  the  blood  vessels  in  the 
abdomen  forces  blood  into  the  peripheral  vessels  and 
the  respiratory  tracts,  preparing  them  for  greater  effort 
at  the  expense  of  the  digestive  tract,  which  temporarily 
ceases  its  function.  The  increased  glycogen  and  more 
rapid  circulation  under  excitement  supplies  nourishment 
to  the  muscles  and  removes  the  products  of  fatigue, 
thus  making  them  capable  of  greater  activity.  The 
constriction  of  the  arteries  and  quicker  clotting  of  the 
blood  serve  to  diminish  the  hemorrhage  in  case  wounds 
are  received  in  the  conflict.  All  together,  emotion  in- 
creases the  energy  of  the  individual  and  lessens  the  lia- 
bility to  injury.  It  is  said  in  this  connection  that  an 
artificially  induced  anger  has  been  used  by  some  indi- 
viduals to  spur  them  to  greater  effort. 

Identical  Reactions  for  All  Emotions.  —  Cannon  con- 
cludes from  his  experiments  that  all  the  activities  he  has 
studied  show  the  same  characteristics  for  all  vigorous 
emotions,  whether  pleasant  or  unpleasant,  whether 
relatively  passive  as  fear  or  active  as  anger.     All  this, 


EMOTION   AND    TE:^IPERAMEXT  479 

then,  must  be  regarded  as  having  a  tendency  to  disprove 
the  extreme  form  of  the  motor  theory  of  emotion,  and 
even  to  narrow  the  applicability  of  the  statement  that 
the  characteristic  quahties  of  emotion  are  dependent 
exclusively  upon  the  bodily  response.  This  theory  was 
also  seriously  questioned  by  Sherrington  as  a  result  of 
experiments  upon  dogs  in  whom  the  connection  between 
body  and  head  had  been  destroyed  by  sectioning  the 
upper  part  of  the  cord.  After  the  operation  they  showed 
the  same  emotional  response  as  before,  had  the  same 
emotions  as  inferred  from  the  reactions  of  the  muscles 
of  the  head.  It  w^as  objected  that  there  may  have  been 
associations  formed  between  the  stimulus  to  the  emo- 
tion and  the  expression  of  the  muscles  of  the  head  by  the 
intermediation  of  the  bodily  responses,  and  that  these 
connections  remained  after  the  sensations  from  bodily 
responses  had  been  cut  off.  This  objection  was  obviated 
by  repeating  the  experiments  on  puppies  only  three 
weeks  old  who  had  had  no  chance  to  form  this  indirect 
association.  The  results  in  this  case  were  the  same  as 
before.  Sherrington  is  con\dnced  that  the  emotion  is 
the  result  of  cerebral  rather  than  of  somatic  reactions. 

Is  Emotional  Quality  Due  to  Bodily  Response  ?  — 
If  we  accept  the  results  of  Cannon  and  Sherrington,  it  is 
evidently  necessar\'  to  ask  how  much  we  can  retain  of 
the  James  theory.  WTiat  Cannon's  experiments  prove 
is  that  there  is  a  large  background  of  physiological  reac- 1 
tion  and  probably  a  large  mass  of  sensations,  common  to  * 
emotions  of  all  t}'pes.  In  psychological  terms  one  can 
say  that  all  emotion  produces  an  excitement  and  that 
this  excitement  has  a  common  quality  no  matter  what 


480  FUNDAMENTALS    OF    PSYCHOLOGY 

the  occasion.  In  this,  emotion  is  not  unlike  affection 
in  which  it  was  found  necessary  to  give  up  the  old  state- 
ments that  the  physiological  responses  for  pleasure  and 
pain  were  opposed.  Now  we  know  that  both  excite 
the  same  changes  in  circulation,  secretion  of  tears,  and 
of  saliva.  To  this  now  we  may  add  that  they  cause  the 
same  secretions  of  adrenalin  and  the  same  diminution 
of  the  reflexes  of  the  alimentary  canal,  and  that  emotions 
differently  aroused  are  also  not  to  be  distinguished  in 
their  fundamental  physiological  effects.  The  possi- 
bihty  remains  that  on  top  of  these  common  elements 
there  may  be  other  responses  sufhciently  distinctive  to 
constitute  the  pecuHar  quaHties  of  the  different  emotions. 
An  answer  to  this  question  requires  more  detailed  inves- 
tigation than  has  been  given  it,  for  in  spite  of  the  long 
controversy  over  the  James  theory,  relatively  few 
accurate  and  extended  observations  have  been  recorded 
of  the  sensations  that  come  with  the  emotions. 

The  Distinguishing  Responses  of  the  Emotions.  — 
If  we  may  attempt  to  supply  the  lack  on  the  basis  of 
chance  observation,  statements  of  novelists,  psychol- 
ogists, and  acquaintances,  it  seems  that  facial  expres- 
sion, the  bodily  posture,  and  a  few  very  general  feelings 
offer  the  most  striking  means  of  differentiation.  There 
are  characteristic  differences  between  facial  expression 
in  grief  and  in  joy.  In  the  one  the  lines  of  the  faces 
are  mostly  concave  downwards,  in  the  other  concave 
upwards.  The  bodily  posture  is  also  different,  drooping 
and  contracted  in  grief,  erect  and  expansive  in  joy. 
Of  the  more  internal  processes  the  most  evident  seem 
to  be  an  elation  in  joy  and  a  depression  with  grief.     One 


EMOTION   AND    TEMPERAMENT  48 1 

gives  a  lightness  that  seems  to  be  localized  in  the  chest, 
the  other  a  heaviness  with  its  seat  in  chest  or  abdomen. 
No  one  of  these  subjective  processes  has  been  referred 
to  a  definite  bodily  organ.  Strains  from  the  head 
may  be  added,  but,  after  all,  the  list  of  bodily  feelings 
that  can  be  clearly  distinguished  is  extremely  short. 
Of  the  specific  emotions  fear  may  be  distinguished  from 
anger  by  the  general  weakness  and  relaxation  of  the  one 
and  the  general  consciousness  of  strength  and  accom- 
pan}dng  acti\dty  of  the  ^other.  Disgust  may  include 
sensations  of  incipient  movements  of  rejection  of  food 
eithej  from  the  mouth  or  alimentary  canal.  Wonder, 
to  complete  Shand's  list  of  primary  emotions,  involves 
relatively  slight  sensations  of  strain  from  the  wide 
open  eyes  or  slightly  open  mouth,  together  with  the 
quiescence  that  comes  from  the  cessation  of  movement. 
That  these  are  part  only  of  the  movements  or  sensations 
involved  in  any  of  the  emotions  considered  is  at  once 
apparent.  That  the  facial  expression  and  bodily  pos- 
ture are  not  sufficient  in  themselves  to  account  for  the 
awareness  of  emotion  is  evident  from  James'  evidence 
that  an  actor  might  act  a  part  and  not  feel  the  emotion. 
Careful  investigation  may  be  able  to  go  much  farther  in 
discovering  the  movements  essential  to  each  emotion. 
For  the  present  we  may  content  ourselves  with  the  state- 
ment that  on  a  background  of  common  responses  which 
furnishes  the  excitement  —  an  element  in  each  emotion — • 
other  reactions  occur  which  possibly  are  characteristic 
of  each  emotion. 

The    Origin    of    Emotional    Responses.  —  For    the 
simpler  emotions  the  nature  of  their  responses  can  be 


482  FUNDAMENTALS    OF    PSYCHOLOGY 

explained  at  once  as  due  to  the  original  instinct.  As 
McDougall  and  others  before  him  put  it,  the  emotion 
is  merely  the  conscious  side  of  the  instinct.  When 
one  runs  away  the  observer  sees  the  running  with  its 
accompanying  pallor  and  calls  it  the  instinct  of  flight, 
while  the  runner  has  the  emotion  of  fear.  McDougall 
parallels  each  of  his  instincts  with  an  emotion.  Disgust 
accompanies  repulsion ;  wonder,  curiosity ;  anger,  pug- 
nacity; elation,  self-assertion,  in  the  same  way  that 
fear  accompanies  flight.  The  explanation  of  instinct 
in  and  of  itself  is  an  explanation  of  emotion.  This 
holds  of  the  larger,  more  useful  responses,  but  many 
of  the  subtler  movements  are  now  merely  expressive. 
Even  these  can  be  explained  directly  as  the  remnants 
of  responses  once  useful  to  the  preservation  of  the 
organism  which  in  many  cases  have  ceased  to  be  useful. 
They  developed  as  did  all  instinct  by  virtue  of  the  sur- 
vival of  the  organisms  that  developed  the  responses, 
or  by  the  dying  out  of  organisms  that  failed  to  develop 
them.  A  large  number  of  the  movements  can  be  shown 
to  be  direct  survivals  of  such  instinctive  responses. 
Running  away,  drawing  back,  or  the  start  of  fear  evi- 
dently removes  the  individual  from  the  neighborhood 
of  the  dangerous  object.  Less  obvious  is  the  utility 
of  the  trembling  and  loss  of  strength  that  come  momen- 
tarily in  fear.  This  may  be  traced  to  a  reduced  form  of 
'  playing  possum  '  or  of  crouching  and  remaining  motion- 
less as  seen  in  the  rabbit  and  other  defenceless  animals. 
It  forces  them  to  remain  motionless  and  thus  enables 
them  to  escape  the  attention  of  pursuers  and  possible 
enemies.     The  cry  of  the  child  is  similarly  useful  in 


EMOTION  AND    TEMPERAMENT  483 

attracting  attention  when  it  is  alone  or  is  uncomff>rt- 
able.  In  each  of  these  cases,  the  conscious  state,  the 
emotion  proper,  is  probably  of  slight  value  but  seems 
to  be  an  unavoidable  accompaniment. 

Darwdn  has  suggested  that  three  other  classes  of  emo- 
tional expression  must  be  recognized  which  serve  still 
further  to  explain  or  at  least  to  classify  the  development 
of  emotional  responses.  These  are  first,  that  when  an 
emotion  or  a  condition  has  given  rise  to  one  form  of 
expression,  a  similar  emotion  or  situation  will  give  rise 
to  a  similar  response.  The  second  is  that,  granted  an 
original  response,  an  opposed  situation  will  give  rise  to 
the  opposite  response.  His  third  class  is  that  in  which 
certain  emotions  result  from  the  direct  overflow  of 
nervous  excitation  without  any  controlling  conditions. 
The  first  of  these  laws  is  illustrated  by  the  sneer,  which 
Darwin  refers  to  the  snarl  of  the  dog.  The  dog  when 
a  possible  enemy  approaches  exposes  the  teeth  and  pre- 
pares for  an  attack.  In  man  the  situation  is  similar 
and  probably  the  mental  attitude  also.  Inconsequence 
man,  too,  draws  back  the  corners  of  the  mouth,  although 
there  is  now  no  thought  of  biting.  Similarly,  in  anger, 
the  nostrils  are  frequently  sKghtly  expanded,  although 
there  is  now  no  particular  utiKty  in  the  motion.  This 
Darwin  would  explain  as  preparation  in  the  animal  for 
admitting  air  while  the  mouth  was  stopped  with  the 
hairy  body  of  the  antagonist.  The  expression  con- 
tinues although  the  original  occasion  no  longer  exists. 
The  second  class  is  more  open  to  objection.  The  best 
illustrations  are  furnished  by  the  movements  of  a  cat 
in  expressing  friendliness.    When  angry,  the  cat  crouches, 


484  FUNDAMENTALS    OF   PSYCHOLOGY 

keeps  the  ears  back  where  they  will  not  be  in  danger  of 
injury,  the  tail  is  down  and  lashing  the  sides.  When 
pleased,  the  opposite  of  this  position  is  taken.  She  is 
erect  and  arches  the  back,  the  tail  is  held  high,  ears 
erect.  There  is  no  particular  reason  for  this  group  of 
responses,  and  Darwin  finds  it  in  the  law  of  antagonism. 
The  mechanism  that  should  lead  to  this  opposed  reaction 
is  altogether  unknown,  and,  as  we  have  seen  in  connec- 
tion with  the  feehngs  and  in  the  recent  studies  of  emo- 
tional expression,  there  is  no  evidence  of  a  tendency  to 
opposition  in  the  expressions.  The  third  class  of  direct 
overflow  includes  all  that  cannot  be  explained  under 
the  other  heads.  Of  course  it  is  not  really  a  new  head, 
as  all  are  due  to  direct  overflow  of  nervous  energy, 
and  this  third  class  includes  only  those  that  cannot  be 
accounted  for  at  all.  Darwin's  instances  are  not  very 
well  authenticated.  One  was  of  an  individual  whose 
hair  turned  gray  over  night  when  he  was  condemned 
to  die  in  the  morning,  reported  on  the  statement  from 
hearsay  of  an  officer  from  India. 

Certain  of  the  emotional  accompaniments,  in  fact 
many  of  those  that  come  from  the  more  external  and 
voluntary  processes,  have  taken  on  a  secondary  value 
as  a  means  of  communication,  as  a  means  of  indicating 
to  another  the  state  of  mind.  The  facial  expressions  di- 
rectly convey  an  impression  of  the  emotion  and  serve 
as  warning  or  encouragement  to  the  companions  to 
cease  or  to  continue  the  Une  of  action  that  they  happen 
to  be  pursuing  at  the  moment.  It  is  probable  that  the 
beginnings  of  articulate  speech  are  to  be  found  in  emo- 
tional expression.     Many  of  the  lower  animals  express 


EMOTION   AND   TEMPERAMENT  485 

emotions  through  sounds,  and  it  seems  possible,  even 
probable,  that  speech  came  from  the  association  of  some 
general  attitude  of  the  individual  making  the  sound  with 
the  sound,  and  that  httle  by  little  other  associations 
came  to  be  made  with  it  until  our  present  fully  devel- 
oped languages  made  their  appearance.  We  can  still 
determine  the  emotional  tone  from  the  modulations  of 
the  voice.  The  loud  tones  and  marked  accents  of  anger, 
the  dragging  monotony  of  the  whine  of  discontent,  the 
softly  modulated  tones  of  affection  show  the  emotional 
state  very  much  more  clearly  than  can  any  expHcit 
statement  in  words.  They  can  be  detected  easily  in 
speech  even  in  a  language  that  we  do  not  at  all  under- 
stand, and  convey  almost  as  much  of  the  emotional  atti- 
tude of  the  speaker  in  an  unknown  language  as  do  words 
in  our  own  tongue.  It  is  not  impossible  that  these  vary- 
ing cadences  were  the  primary  forms  of  expression  and 
communication  and  that  the  words  as  they  developed 
have  been  fitted  into  them. 

In  the  emotions  of  our  second  class,  due  to  thwarting 
or  furthering  of  acquired  purposes,  the  explanation  of 
why  the  movements  should  be  aroused  is  not  so  direct. 
As  was  said,  the  bodily  reaction,  if  one  judge  from  im- 
mediate consciousness,  is  the  same  as  in  the  other 
group.  Instead,  however,  of  having  as  the  occasion  for 
the  reaction  some  stimulus  that  has  an  inherited  con- 
nection with  it,  it  is  aroused  by  an  idea  or  event  that 
must  have  become  associated  with  it  through  experience. 
Thus,  anger  or  sorrow  over  the  loss  of  a  social  honor 
cannot  be  said  to  have  a  definitely  instinctive  origin, 
but  the  bodily  reaction  may  be  little  different  from 


486  FUNDAMENTALS    OF   PSYCHOLOGY 

that  excited  by  loss  of  a  dinner  and  may  continue  for 
a  much  longer  time  and  with  greater  intensity.  Part 
of  this  transfer  of  emotional  response  from  immediately 
instinctive  to  more  recently  developed  processes  may  be 
explained  on  the  analogy  of  Darwin's  laws.  A  vague 
similarity  between  the  more  complex  and  the  simpler 
situation  leads  to  the  arousal  of  the  same  instinctive  re- 
sponses for  both.  The  social  honor  is  a  prize  which 
through  the  effect  of  life  in  the  community  has  become 
as  desirable  as  a  bit  of  food.  When  it  is  lost,  the 
reaction  is  the  same  as  that  which  follows  the  loss  of 
something  whose  appeal  is  instinctive.  Whatever  the 
mechanism,  certain  it  is  that  the  interrelations  of 
acquired  tendencies  and  their  interaction  with  the 
environment  do  lead  to  responses  identical  with  the 
purely  instinctive.  One  may  add  to  these  the  assump- 
tion of  Dewey  that  much  of  the  quality  of  emotions 
may  be  due  to  conflict  or  cooperation  between  the 
habitual  responses.  These  acquired  responses  might 
stand  to  the  instinctive  responses  as  the  acquired  ideals 
and  needs  to  the  innate  or  instinctive.  Possibly  the 
interaction  of  systems  of  experience  or  of  neurones  might 
give  rise  immediately  to  a  conscious  quality.  If  one 
were  to  take  the  result  of  Sherrington's  experiments  at 
full  value  it  would  be  necessary  to  assume  some  such 
effects  and  qualities  of  purely  central  interactions. 
Two  loopholes  in  his  argument  make  this  conclusion 
doubtful.  His  experiments  left  his  pups  with  a  con- 
nection between  the  cortex  and  the  facial  muscles,  so 
that  the  latter  might  give  rise  to  the  emotional  content. 
Secondly,  his  only  evidence  of  emotion  was  the  facial 


EMOTION   AXD    TE^IPEILAMEXT  487 

expression.  Really  all  that  his  experiments  prove  is 
that  one  may  have  the  facial  expression  of  an  emotion 
without  any  connection  between  the  cortex  and  the 
trunk  or  Hmbs.  WTiile  much  remains  to  be  done  upon 
relating  particular  emotions  to  bodily  responses,  there 
is  every  reason  to  beHeve  that  the  quality  of  the  emo- 
tion, whether  it  be  immediately  instinctive  in  origin  or 
arise  from  interrelations  of  purposes  and  acquired 
ends,  is  due  in  large  part  to  reflex  acti\ities.  Most  of 
the  response  is  common  to  all  sorts  of  emotion,  but  added 
quahties  probably  give  much  of  the  distinctive  tone  to 
the  separate  emotions. 

The  Kinds  of  Emotion.  —  WTiile  the  quality  of  emotion 
may  be  accepted  as  in  large  part  determined  by  the 
bodily  resonance,  the  names  are  not  given  to  emotions 
on  the  basis  of  these  quahties.  This  may  be  due  in 
part  to  the  large  mass  of  sensations  common  to  all  emo- 
tions and  in  part  to  the  fact  that  emotions  are  usually 
named  after  they  have  ceased  or  by  an  observer  if  named 
at  all.  During  the  emotion  one  is  too  much  interested 
in  other  things  to  consider  its  quahties.  In  conse- 
quence names  are  usually  given  on  the  criteria  of  the 
causes  of  the  emotion  or  of  its  outcome.  Perhaps,  too, 
the  fact  that  fear  and  anger,  love  and  jealousy,  and 
other  emotions  are  so  nearly  indistinguishable  is  to  be 
found  partly  in  the  fact  that  one  changes  into  another 
wdth  great  rapidity.  Anger  is  distinct  from  fear  only 
in  the  consciousness  of  power  or  weakness  toward  the 
intruding  man  or  object,  and  this  changes  from  moment 
to  moment  as  the  situation  is  faced.  One  first  fears, 
then  becomes  angry,  and  again  is  afraid  as  long  as  one 


FUNDAMENTALS    OF   PSYCHOLOGY 

is  living  through  the  experience.  When  the  situation 
is  properly  classified,  when  it  is  settled  that  one  is  stronger 
and  must  fight,  or  is  weaker  and  must  run,  the  emotion 
is  said  to  take  on  a  new  phase,  perhaps  even  to  disap- 
pear. If  one  assume  a  changing  response  or  perhaps 
a  conflict  of  responses  during  the  emotional  state,  it  is 
no  wonder  that  the  physical  accompaniments  of  opposed 
emotions  should  be  identical.  Both  physically  and 
mentally  the  two  fuse,  and  one  may  not  be  sure,  even  after 
the  event,  whether  fear  or  anger  was  dominant.  This 
rapid  alternation  of  expressions,  taken  together  with 
the  fact  that  there  are  always  identical  responses  in 
the  sympathetic  or  autonomic  system,  makes  classi- 
fication in  practice  difficult  and  then  largely  in  terms 
of  the  intellectual  antecedents,  the  nature  of  the 
object,  and  the  outcome  of  the  adventure.  It  is 
this  that  led  the  popular  mind  and  earlier  philosophers 
to  the  classification  of  emotions  in  other  than  motor 
terms. 

Relation  of  Emotion  to  Other  Mental  Processes.  — 
Emotions  have  many  and  close  relations  with  the  other 
mental  processes.  In  many  cases  we  can  trace  the 
development  of  emotions  to  the  association  of  ideas. 
The  occasion  for  the  emotion  is  not  infrequently  to  be 
found  in  a  recalled  event.  The  reaction  in  this  case  is 
usually  not  so  strong  as  that  made  to  the  original  event 
or  sensation,  but  has  many  of  its  characteristic  qual- 
ities. Often  it  seems  that  there  is  an  association  be- 
tween emotional  states  themselves.  After  some  pleas- 
ant emotion  the  liability  to  painful  response  is  de- 
creased, while  after  a  disagreeable  one,  all  may  tend  to 


EMOTION   AND   TE:MPERAMENT  489 

produce  a  disagreeable  emotion.  After  one  success  has 
produced  elation  every  event  assumes  a  roseate  hue,  — 
one  is  easily  pleased,  the  emotion  of  joy  comes  of  it- 
self. After  failure,  doubt  assails  with  each  new  venture. 
Similarly,  after  one  fright,  fear  is  easily  aroused.  In 
short,  any  intense  emotion  leaves  a  predisposition  to  the 
same  or  similar  emotions. 

Emotion  has  so  many  similarities  to  feehng  that  one 
may  with  difhculty  draw  the  Hne.  Almost  all  emotions 
are  aftectively  toned.  The  exception  is  to  be  found  in 
surprise.  Kulpe  would  ehminate  it  from  the  Hst  of 
emotions  because  it  lacks  affective  tone,  emphasizing 
the  close  relation  that  he  beheves  to  exist  between  affec- 
tion and  emotion.  It  is,  however,  in  most  of  the  lists. 
The  similarities  between  surprise  and  the  other  emo- 
tions are  twofold.  First,  it  is  characterized  by  motor 
responses,  second,  by  a  break  in  the  train  of  thought  or 
other  occupation.  Nor  is  it  altogether  true  that  sur- 
prise is  devoid  of  affective  accompaniments ;  rather  is 
it  to  be  said  that  the  character  of  that  accompaniment 
is  uncertain.  Surprise  is  in  the  majority  of  cases  either 
pleasant  or  unpleasant,  but  the  same  term  is  used  for 
both  pleasant  and  unpleasant  surprises.  The  differ- 
ences between  feehng  and  emotion  are  largely  in  degree. 
The  affective  tone  is  usually  stronger  in  emotion.  As 
the  name  impKes,  the  motor  responses  are  more  strik- 
ing and  more  fully  developed.  It  is  generally  true,  too, 
that  the  cause  or  occasion  for  the  emotion  is  to  be  found 
on  the  perceptual  level,  in  a  stimulus  as  appreciated, 
rather  than  in  the  bare  sensation.  No  one  of  these  dis- 
tinctions   can   be    appHed    without   exception,    but   all 


490  FUNDAMENTALS    OF   PSYCHOLOGY 

taken  together,  now  one,  now  another  predominating, 
serve  to  draw  a  distinction  in  practice. 

In  their  relations  to  voluntary  acts  emotions  have 
opposed  effects,  dependent  probably  upon  whether 
we  consider  one  or  the  other  type  of  emotions.  In 
those  which  have  an  ideational  occasion  and  are  to  be 
regarded  as  interferences  with  the  acquired  ends  of  the 
individual,  the  effect  of  emotion  is  generally  to  in- 
crease the  motor  efficiency,  at  least  in  the  coarser  acts. 
The  more  primitive  emotion,  the  subjective  accompani- 
ment of  an  intense  instinctive  response  to  an  external 
stimulus,  is  more  Hkely  to  inhibit  voluntary  movements, 
particularly  the  more  refined  and  accurate  movements, 
although  even  here  the  actual  strength  is  increased  and 
the  individual  is  probably  more  efficient  in  a  fight  or  in 
flight.  Numerous  exceptions  may  be  found  to  both 
rules  and  exceptions.  Fear  or  even  anger  may  leave  one 
practically  helpless,  with  a  tremor  or  weakness  that 
prevents  all  movement  for  a  time  and  then  probably 
increases  the  capacity.  Again,  sfight  emotion  may  en- 
able one  to  carry  through  relatively  dehcate  activities, 
those  of  an  artistic  character,  e.g.,  that  one  might  not  be 
capable  of  in  a  calm  moment. 

Emotional  Control.  —  One  may  -control  emotions  in 
some  degree.  The  only  real  control  is  that  effected 
at  the  source.  The  nature  and  degree  of  an  emotion 
depend  very  largely  upon  the  way  a  situation  is  classified. 
An  event  frequently  may  be  referred  to  more  than  one 
head  and  will  arouse  a  different  emotion  under  each 
of  these  classifications.  A  human  brain,  presented 
to  a  class  with  numerous  references  to  what  the  individ- 


EMOTION  AXt)   TEMPEiLAMENt  491 

ual  must  have  thought  with  it,  and  with  other  remarks 
that  emphasize  the  personal  side,  is  very  Ukely  to  arouse 
intense  emotions ;  but,  if  considered  only  in  connection 
-^ith  tracts  and  structure,  may  excite  mere  scientific 
interest.  ]\Iany  of  the  events  of  everyday  Kfe  show  the 
same  phenomenon.  Classify  a  remark  or  the  man  who 
makes  a  remark  in  one  way  and  you  become  angry, 
regard  it  or  him  in  another  light  and  you  are  only  mildly 
amused.  !Much  also  may  be  done  by  preventing  ex- 
pression, although  this  too  can  be  controlled  only  by 
changing  the  attitude  or  in  directing  attention  to  some- 
thing else  until  the  occasion  for  the  emotion  is  past. 
Either  method  of  control  becomes  much  more  effective 
after  practice.  Like  everything  else,  attitude  and  re- 
sponse become  habitual ;  instinctive  reactions  are  changed 
by  habit.  The  physician  or  surgeon  can  look  upon 
patients  as  cases  and  neglect  the  more  personal  relations. 
Such  professional  attitudes  are  taken  by  members  of 
nearly  all  professions  with  the  corresponding  develop- 
ment or  suppression  of  emotion  and  emotional  expres- 
sion. 

Summary.  —  We  may  think  of  emotion,  then,  as  a 
disturbance  of  the  usual  or  normal  course  of  any  suc- 
cession of  thoughts  or  activities  by  the  intrusion  of  a 
new  or  extraneous  event.  This  event  results  in  a  more 
or  less  prolonged  disturbance  of  the  activities,  accom- 
panied by  many  useless  and  incoordinated  responses, 
and  by  intense  affection.  It  is  possible  to  distinguish 
two  t}'pes  of  emotion,  or  at  least  two  extremes  of  emo- 
tion. One,  usually  the  more  violent  but  usually  of  short 
duration,  is  directly  dependent  upon  instinct,  both  in 


492  FUNDAMENTALS    OF   PSYCHOLOGY 

condition  and  response.  This  is  the  type  that  may  be 
defined  as  the  mental  accompaniment  of  an  instinct. 
The  second  type,  vv^hich  is  usually  of  sHghter  intensity 
and  greater  duration,  is  conditioned  by  the  thwarting  or 
furthering  of  the  system  of  purposes  developed  by  the 
individual  upon  an  instinctive  basis.  Even  for  this 
class  the  responses  are  also  of  instinctive  origin.  In 
this  latter  case,  however,  we  must  look  to  the  mental 
antecedents  rather  than  to  the  physical  responses  as 
the  cause  of  the  emotion,  and  as  the  determinant  of  the 
type  of  emotion  that  shall  be  induced  by  any  event. 
The  bodily  reverberation  depends  upon  the  antecedent 
mental  states  rather  than  being  itself  a  first  cause  and  as 
constituting,  through  the  sensations  it  excites,  the  entire 
emotion.  This  is  not  to  deny  the  important  part  played 
by  the  movements  in  giving  color  to  emotion ;  it  merely 
insists  that  other  factors  must  be  considered  in  dis- 
cussing its  origin. 

Sentiment.  —  Sentiment  is  ordinarily  used  to  desig- 
nate the  milder,  more  lasting  forms  of  emotion.  Shand 
has  varied  the  apphcation  of  the  term  to  indicate  the 
antecedent  condition  of  emotions,  the  system  of  impulses 
that  dominates  the  individual,  which,  when  furthered  or 
liindered,  gives  rise  to  the  emotion.  The  sentiments 
are  for  him  dependent  upon  the  instincts,  but  the  in- 
stincts are  in  turn  modified  and  developed  by  experi- 
ence. The  two  great  systems  are  love  and  hate.  These 
are  fundamental,  constitute  the  impelling  forces  of  all 
activity,  and  give  rise  to  emotion  when  acted  upon  by 
particular  events.  When  aroused  they  are  or  may  be 
directed  toward  particular  persons  or  objects.     They 


EMOTION   AND   TEMPEILA.AIENT  493 

approach  the  particular  emotion  rather  than  the  fun- 
damental tendencies  which  constitute  the  background, 
the  impelhng  force  needed  for  the  development  of  emo- 
tion. This  definition  emphasizes  the  characteristic  of 
duration  impHed  in  the  usual  meaning  of  the  word  and 
has  been  accepted  by  ^IcDougall  and  Stout.  There 
is  no  doubt  also  that  there  is  need  for  some  name  to 
designate  the  systems  of  impulses  or  purposes,  but  some 
word  implying  greater  force  would  be  better  than 
sentiment,  since  these  systems  are  the  forces  behind  all 
volimtary  activities,  mental  and  physical,  as  well  as  the 
occasions  for  the  emotions.  What  is  designated  is  more 
like  what  is  usually  called  desire  or  a  system  of  desires 
than  sentiment.  While  the  authority  behind  this  defi- 
nition of  the  word  entitles  it  to  respect,  sentiment 
seems  better  suited  to  designate  the  mild  continued 
emotion,  its  more  usual  meaning. 

Mood  and  Passion.  —  Mood  is  a  predisposition  to  an 
emotion  of  comparatively  short  duration.  It  may  be 
due  to  physical  causes.  Lack  of  sleep,  a  fit  of  indiges- 
tion, and  many  other  indispositions  predispose  to  un- 
pleasant emotions,  while  good  health  and  rest  conduce 
to  pleasant  emotions  or  sentiments.  Moods,  too,  de- 
velop from  earlier  emotions.  A  disagreeable  emotion, 
as  was  said  above,  leaves  a  tendency  to  other  unpleasant 
emotions,  and  this  is  a  mood.  Moods,  then,  are  rather 
dispositions  to  emotions  than  any  particular  kind  of 
consciousness  or  behavior  of  themselves.  Passion, 
like  sentiment,  has  been  used  in  various  ways  at  different 
times  and  by  different  men,  now  being  extended  to  cover 
the  entire  field  of  pleasant  and  unpleasant  acts  or  men- 


494  FUNDAMENTALS    OF   PSYCHOLOGY 

tal  states,  and  again  restricted  to  the  more  violent  exhi- 
bitions of  the  emotional  reaction.  At  present  it  can 
hardly  be  said  to  have  any  technical  meaning.  As  in 
the  popular  sense,  it  most  frequently  designates  the 
more  violent  forms  of  emotion. 

Temperament.  —  Temperament  is  a  word  with  a 
long  pedigree  in  psychological  usage  and  one  that  has 
undergone  little  change  in  appHcation  since  first  intro- 
duced. Galen  recognized  four  humors  in  the  body, 
blood,  phlegm,  black  bile,  and  yellow  bile,  and  assumed 
that  the  disposition  of  the  individual  was  largely  deter- 
mined by  the  one  that  was  dominant.  These  gave  rise 
to  four  principal  temperaments,  the  sanguine,  the  melan- 
chohc,  choleric,  and  phlegmatic.  These  names  still 
persist,  although  they  have  taken  on  slightly  different 
forms  at  the  hands  of  different  psychologists  and  in  the 
popular  mind.  Thus  Wundt  makes  the  temperaments 
depend  upon  combinations  of  rate  and  strength  of  re- 
sponse in  a  given  individual.  The  sanguine  is  said  to  be 
quick  and  weak,  the  choleric,  quick  and  strong,  the 
melanchoHc,  slow  and  strong,  the  phlegmatic,  slow  and 
weak.  This  corresponds  to  certain  of  the  characteristics 
of  the  terms  as  popularly  used,  but  omits  what  seems 
the  most  important,  the  tendency  to  pleasant  or  to  un- 
pleasant emotions.  On  the  whole,  the  schematism  of 
Wundt  has  little  to  recommend  it  over  the  looser  appli- 
cation of  the  terms  in  popular  speech.  All  together  it 
can  hardly  be  said  that  we  know  more  about  tempera- 
ments than  that  individuals  differ  in  their  susceptibility 
to  the  different  emotions.  At  present  there  is  no  com- 
plete classification  of  these  dispositions.     The  ideal  of 


EMOTION   AND    TEMPERAMENT 


495 


Galen,  that  one  might  group  individuals  in  such  a  way 
that  it  would  be  possible  to  determine  what  mental  and 
physical  capacities  and  dispositions  were  necessarily 
associated  and  find  some  simple  test  that  would  deter- 
mine to  which  of  these  classes  each  individual  belonged, 
is  almost  as  remote  to-day  as  it  was  when  Galen  wTote. 

REFERENCES 

James  :  Principles  of  Psychology,  vol.  ii,  ch.  xxv. 

Shaxd  :   Foundations  of  Character. 

Darwin  :  Expression  of  Emotions  in  Animal  and  Man. 

RiBOT :  Psycholog>^  of  Emotions. 

Jastrow  :  Temperament  and  Character. 


CHAPTER  XV 

THE  GENERAL   PRINCIPLES  OF  ACTION  — WILL 

The  final  outcome  of  all  thought,  of  all  mental  pro- 
cesses whatsoever,  is  action.  In  connection  with  the 
nervous  system  it  was  seen  that  all  stimulations  tend  to 
find  an  outlet  through  the  motor  nerves  and  muscles, 
and  movements  play  an  important  part  in  almost  all 
mental  states.  Movements  accompany  all  acts  of 
attending,  and  several  authorities  explain  the  fact  of 
attention  itself  by  the  movements  called  out,  rather 
than  by  the  antecedent  mental  states.  In  perception, 
movements  are  used  as  a  means  of  explaining  space, 
time,  and  rhythm ;  recognition  is,  for  some  authorities, 
merely  a  revival  of  old  movements.  We  find  many 
writers  who  explain  many  if  not  all  of  the  essentials 
of  the  reasoning  processes  in  terms  of  movement.  Either 
as  beginning,  intermediate  stage,  or  end  of  every  mental 
state  we  find  that  action  has  an  important  place  in  fact 
or  theory. 

We  may  assume  in  our  present  chapter  that  action  is 
the  real  aim  of  life,  and  that  most  of  the  operations  so  far 
discussed  are  preliminary  to  it.  This  action  may  follow 
immediately  upon  them  or  may  be  delayed  for  a  consider- 
able period.  Here,  however,  we  are  more  concerned 
to  see  how  the  other  processes  lead  to  action,  than  to 

496 


THE    GENERAL   PRINXIPLES    OF   ACTION WILL      497 

understand  the  part  that  movement  plays  in  them. 
In  the  first  place,  we  may  assert  \vith  some  conhdence, 
on  the  basis  of  practically  universal  agreement  of  the 
psychologists  of  to-day,  that  there  are  no  new  forces, 
nor  even  any  absolutely  new  laws  involved  in  the  con- 
trol of  action.  All  mental  states  give  rise  to  movements 
of  greater  or  less  extent,  and,  on  the  other  hand,  move- 
ment as  a  psychological  process  can  be  explained  only 
in  terms  of  certain  mental  states  already  discussed. 
Were  we  to  give  a  complete  explanation  of  movement, 
we  should  have  a  review  of  each  of  the  preceding  chap- 
ters with  an  appendix  on  the  way  in  which  movement 
resulted  from  it.  We  can  at  most  add  the  appendix  in 
this  chapter.  Assuming  that  the  fundamental  princi- 
ple of  all  action  is  that  all  excitations  tend  to  pass  over 
from  the  sensory  to  the  motor  neurones,  we  may 
raised  several  fundamental  questions  in  connection  with 
this  process  which  may  be  discussed  or  put  aside  now 
before  we  proceed  to  the  details. 

Sensation  and  Movement.  —  One  of  the  most  im- 
portant is  whether  the  sensory  excitation  that  leads  to 
movement  must  be  accompanied  by  sensation.  The 
evident  answer  is  that  sensation  may  or  may  not  accom- 
pany the  process.  Some  assert  that  normally  all  move- 
ment comes  from  sensation,  but  we  have  also  the  opposite 
view  that  all  sensation  is  aroused  by  the  excitation  of 
the  motor  neurone  or  even  by  the  movement  itself. 
Neither  of  these  extreme  views  need  concern  us  here. 
We  may  be  content  with  the  statement  that  the  excita-- 
tion  of  motor  processes  certainly  often  takes  place  with 
no  accompan}dng  sensation,  and  that  all  that  is  really 

2K 


498  FUNDAMENTALS   OF   PSYCHOLOGY 

necessary  for  the  movement  is  the  previous  excita- 
tion of  some  sensory  organ  or  sensory  neurone.  This 
latter  may  come  through  some  indirect  path  involving 
a  memory,  or  the  cortical  cells  ordinarily  active  in  mem- 
ory. The  natural  thing  is  for  the  sensory  process  to 
discharge  into  movement.  What  really  needs  explana- 
tion is  why  at  times  the  sensory  excitations  do  not  cause 
movements.  In  the  complete  sense  they  probably  never 
fail  to  arouse  some  response,  but  it  is  frequently  too 
slight  to  be  noticed.  The  fundamental  fact  of  action 
in  general  needs  no  special  explanation. 

Is  Conscious  or  Unconscious  Action  Primary?  —  An- 
other question  that  has  been  much  discussed  is  whether 
conscious  or  unconscious  action  comes  first.  It  has 
been  argued  by  Titchener,  Cope,  and  others  that  the 
original  actions,  the  action  of  the  lowest  animal  forms, 
were  all  conscious,  that  they  had  sensations  fully  devel- 
oped as  the  occasion  of  the  action,  and  were  conscious 
of  the  results  of  the  action  and  lost  that  consciousness 
with  use.  The  other  theory  places  the  unconscious  re- 
flex act  first  and  makes  consciousness  appear  at  some 
higher  stage.  Each  is  dependent  upon  indirect  argu- 
ments. The  holders  of  the  first  theory  give  as  evidence 
the  fact  that  in  man  many  movements,  once  fully 
conscious,  lapse  through  repetition  into  automatic  acts, 
or  acts  that  have  no  conscious  accompaniments,  and 
assert  that  the  development  of  movement  in  the  race 
must  have  run  the  same  course.  The  other  view  rests 
upon  the  assumption  that  evolution,  in  action  as  in 
other  processes,  passes  from  the  simple  to  the  complex, 
and  that  the  reflex  is  the  simplest  form  of  action.    The 


THE    GENERAL   PRINCIPLES    OF   ACTION WILL      499 

only  difficulty  lies  in  the  impossibility  of  saying  where 
in  the  course  of  animal  development  the  conscious  form 
of  movement  might  have  made  its  appearance.  There 
seems  to  be  no  point  from  the  simplest  organism  to 
man  where  one  can  say  with  full  assurance  that  action 
takes  a  completely  new  form.  Since  we  have  no  evi- 
dence as  to  whether  the  lowest  forms  are  or  are  not 
conscious,  and  in  man  no  e\ddence  that  first  movements 
are  really  the  outcome  of  conscious  processes,  it  is  simpler 
to  assume  that  reflexes  are  the  original  movements  and 
to  keep  the  question  of  the  presence  of  consciousness 
as  much  in  the  background  as  possible.  We  shall  find 
that  even  in  man  the  relation  of  consciousness  to  action 
offers  many  unsolved  problems. 

The  Methods  of  Learning.  —  Starting  with  the  single 
assumption  that  movements  always  follow  upon,  and 
are  the  outcome  of,  sensory  stimulations,  the  first  ques- 
tion that  meets  us  is  what  it  is  that  determines  what 
movement  shall  follow  upon  any  given  stimulation. 
We  have  seen  that  certain  connections  are  present 
in  the  organism  at  birth,  the  result  of  the  heredity  and 
evolution  of  the  individual  and  of  the  species.  These 
innately  determined  movements  are  the  reflexes  and 
instincts.  The  greater  number  of  movements  in  man 
and  in  the  higher  animals  are  found  to  be  the  outcome 
of  learning,  to  be  due  to  connections  formed  after  the 
birth  of  the  indi\ddual.  The  problem  of  how  these 
connections  are  formed  is  one  that  may  be  said  to  have 
found  its  answer  within  the  last  twenty  years  in  the 
studies  of  animals. 

The  experiments  were  begun  by  Thorndike,  who  tested 


Soo 


FUNDAMENTALS    OF   PSYCHOLOGT^ 


the  methods  by  which  a  cat  learned  to  escape  from  a 
box  that  had  a  door  fastened  by  a  simple  catch,  a  button 
that  could  be  turned,  or  a  bolt  that  might  be  drawn 
by  pulling  a  string  hanging  down  inside  the  box.  To 
make  sure  that  the  cat  would  make  an  effort,  it  was 
hungry  when  put  into  the  box  and  food  was  in  sight  on 
the  outside.     The  process  of  learning  has  been  found 


Fig.  go.  —  Animal  problem  box.     (From  Thorndike,  "  Animal  Intelligence.") 

to  depend  in  practically  all  animals  upon  the  presence 
of  random  movements,  —  is  one  of  trial  and  error.  The 
cat  makes  a  large  number  of  movements  of  all  sorts, 
tries  to  force  herself  through  all  promising  openings, 
bites  at  all  projections,  scratches,  and  mews;  in  fact, 
she  exhausts  all  the  acts,  reflex,  instinctive,  and  habitual, 
that  she  has  at  her  command.  Sooner  or  later  one 
presents  itself   that  happens   to   open   the   door.     She 


THE    GEXEIL\L    PRI^XIPLES    OF    ACTION WILL       5OI 

scratches  at  the  button  and  by  pure  chance  turns  it. 
WTien  the  door  is  open  she  walks  out.  But  one  successful 
movement  does  not  teach  her  the  method  of  opening 
the  door.  \Mien  put  in  again,  she  goes  through  a  series 
of  random  movements  a  second  time,  and  again  ^\ill 
hit  upon  the  correct  response  by  chance.  It  is  only 
after  a  number  of  successes  —  how  many  varies  with  the 
intelligence  of  the  animal  —  that  the  right  move- 
ment mil  be  begun  at  once  when  the  animal  is 
put  into  the  box.  Each  trial  will,  on  the  average, 
require  less  time  than  the  one  that  preceded  it, 
but  there  are  many  variations  owing  to  chance 
difficulties. 

This   process    of    learning    by   trial  and   error 
governs  all  of  the  learning  of  animals  so  far  ex- 
perimented upon  from  the  very  lowest 
to  man.     How  low  depends  upon  what 

is  meant 

^  by  leam- 

^    ^  T 1 ^ 1 •  T 

^inZ  mg.     In 

Fig.  91.  —  Cur\-e  of  learning  in  dogs.     Height  shows  time  required     the  early 
for  hitting  upon  each  correct  response.     (From  Thomdike.)  , 

cnapters 
it  was  noted  that  Jennings  found  that  movements  were 
modified  by  the  results  of  earHer  actions  even  in  the 
unicellular  organisms.  The  Stentor,  e.g.,  would,  when 
slightly  stimulated,  at  first  bend  to  one  side  and  then 
later  give  up  all  responses.  If  the  stimuK  were  made 
more  intense,  it  would  first  bend  away  sharply  and  then, 
after  several  responses  which  failed  to  remove  it  from 
the  excitation,  would  release  its  hold  and  swim  away. 
This,  the  most  rudimentary  form  of  learning,  is  never- 


502  FUNDAMENTALS    OF    PSYCHOLOGY 

theless  learning.  From  that  point  on,  more  and  more 
complex  movements  may  be  acquired  as  the  organism 
increases  in  complexity.  The  essentials  of  the  learning 
process  in  animals  seem  to  be  that  any  problem  must 
be  solved  by  chance  at  first ;  that,  after  the  right  move- 
ments have  been  hit  upon  a  sufficient  number  of  times,  a 
connection  is  established  between  a  certain  stimulus 
or  group  of  stimuli  and  the  movement  in  such  a  way  that 
the  stimulus  tends  at  once  to  call  out  the  corresponding 
movement. 

This  still  leaves  open  the  question  as  to  what  brought 
the  so-called  chance  response  in  the  first  place.  If  we 
turn  back  to  the  nervous  system,  it  may  be  said  that  a 
given  sensory  impression  stimulates  a  sensory  neurone, 
which  in  its  turn  has  axones  connected  with  a  number 
of  motor  neurones.  The  synapse  to  one  of  the  motor 
neurones  probably  offers  least  resistance  and  the  im- 
pulse passes  across  that.  If  the  result  which  comes 
from  the  act  gives  pleasure  or  does  not  remove  the  un- 
pleasant stimulus,  a  new  set  of  responses  will  be  started 
as  the  stimulus  becomes  strong  enough  to  open  less 
permeable  synapses.  If,  e.g.,  the  cat  does  not  escape, 
get  the  meat,  and  in  consequence  begin  the  instinctive 
responses  involved  in  eating,  then  new  synapses  will 
be  opened  and  other  movements  result  until  some  change 
in  the  stimulation  starts  a  new  series  of  responses.  It 
should  be  remembered  that  there  is  not  one  stimulus 
but  many,  and  that,  as  attention  changes,  new  stimuli 
come  which  also  make  possible  new  movements.  When 
the  movement  has  been  made,  the  same  stimulus  will 
produce  the  same  movement,  and  each  repetition  reduces 


THE    GEXEIL^L   PRIN'CIPLES    OF   ACTION  —  WILL       503 

the  resistance  at  the  sAnapse  as  in  the  formation  of  asso- 
ciation. In  animals  and  in  the  ordinary  learning  of 
man,  each  movement  is  the  result  of  instinctive  responses 
or  of  earlier  habits.  Watson  asserts  that  there  is  no 
real  formation  of  new  connections  in  learning,  but  that 
all  is  due  to  the  elimination  of  certain  of  the  unnecessary 
movements  in  the  first  trials.  His  theory  is  that  the 
inherited  connections  usually  offer  roundabout  paths 
between  stimulus  and  movement.  This  series  of  re- 
sponses is  innate.  Trial  and  error  finally  make  a  more 
direct  connection  between  the  stimulus  and  the  success- 
ful act.  On  this  theory  learning  could  never  lead  to 
absolutely  new  connections.  It  could  only  shorten  the 
course.  Undoubtedly  a  large  part  of  learning  is  of  this 
character. 

How  Far  are  New  Connections  Formed  in  Learning? 
—  In  man.  however,  there  seem  to  be  cases  in  which 
there  is  no  natural  nervous  connection  at  the  synapses, 
or  at  least  in  which  the  instinctive  connection  is  very 
weak  and  in  which  learning  takes  place  through  a  spread 
of  impulses  over  synapses  very  slightly  permeable. 
Thus,  in  learning  to  move  the  ears  in  the  experiments 
that  Bair  carried  out,  a  connection  was  formed,  a  path 
of  discharge  was  opened  to  a  muscle  not  ordinarily  under 
voluntary  control.  Here  there  seemed  to  be  a  gradual 
spread  of  impulse  from  the  usual  channels  to  more  and 
more  unusual  ones,  until  finally  it  chanced  to  find  the 
old  path  to  the  retrahens  muscle,  the  muscle  that  pulls  the 
ear  back.  Then  repetition  stamped  in  the  connection 
until  it  could  be  repeated  at  will.  Another  case  of  the 
formation  of  new  connections  is  furnished  by  the  surgical 


504  FUNDAMENTALS    OF   PSYCHOLOGY 

operation  that  replaces  an  impaired  nerve  by  another 
with  an  altogether  different  central  connection.  Thus, 
when  there  has  been  paralysis  of  the  nerve  innervating 
the  flexor  muscle  of  the  arm,  it  has  been  possible  to 
divide  the  nerve  supplying  the  extensor  muscle  and 
connect  one  part  of  it  with  the  injured  flexor  muscle. 
When  it  has  regenerated,  the  nerves  that  previously 
produced  extension  of  the  arm  now  carry  the  impulses 
which  produce  flexion.  Here  evidently  we  cannot  be 
dealing  with  a  dropping  out  of  old  connections  but  must 
have  the  formation  of  altogether  new  ones.  It  would 
seem,  too,  that  the  movements  established  after  recovery 
from  infantile  paralysis  must  be  due  to  the  transmission 
of  impulses  over  new  paths  and  hence  are  the  result  of 
forming  new  connections  between  sensory  and  motor 
neurones.  All  three  of  these  involve  formation  of  con- 
nections that  are  not  definitely  present  at  birth ;  in  the 
second  instance,  in  fact,  they  follow  paths  and  produce 
movements  the  reverse  of  those  that  are  innate.  Indeed, 
much  evidence  is  accumulating  that  there  is  consider- 
able variation  in  the  paths  followed  during  the  same 
function  of  the  cortex.  If  confirmed,  this  fact  would 
prove  that  the  formation  of  new  connections  is  the  rule 
rather  than  the  exception. 

The  Acquisition  of  Skill.  —  In  the  adult  man  the 
most  important  practical  problem  of  learning  is  how 
series  of  acts,  already  under  control  in  isolation,  may  be 
united  into  a  single  series,  may  be  made  to  constitute 
a  unitary  group.  This  is  what  happens  when  one  ac- 
quires skill  in  any  game  or  occupation.  A  number  of 
investigations  have  been  carried  out  on  problems  of 


THE    GEXEILIL   PRI^XIPLES    OF   ACTION  —  WILL      505 

this  sort.     Btyan  and  Harter  investigated  the  learning 
of  the  telegraphic  language ;    Swift,  t>'pewriting,  toss- 


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Fig.  92.  —  Curv^e  of  learning  to  write  on  the  tj-pewriter.  The  horizontal 
distances  show  the  number  of  days  of  practice ;  the  vertical,  the  number  of  words 
written  in  an  hour.  Cur\'e  i  shows  the  progress  during  the  original  practice; 
cur\-e  2,  the  results  of  nine  days'  practice  after  an  interval  of  two  years  and  thirty- 
five  daj's.     (From  Swift.) 

ing  balls,  and  learning  Russian ;   Bair  and  Book,  type- 
writing.    All    obtained    the    same    general    result    that 


5o6  FUNDAMENTALS    OF    PSYCHOLOGY 

skill  comes  rapidly  at  first  and  then  more  slowly,  and 
that  in  the  course  of  the  work  there  are  many  periods 
in  which  no  progress  is  made,  followed  by  periods  of 
rapid  improvement.  In  each  of  these  tasks  the  in- 
dividual movements  are  known  in  advance.  One  can 
press  the  key  of  a  telegraph  instrument  or  of  the  type- 
writer or  toss  a  ball  at  the  start.  What  is  necessary 
is  to  organize  the  whole  so  that  one  element  shall 
start  the  next,  and  all  shall  be  carried  on  together 
without  false  movements,  and  as  rapidly  as  is  possi- 
ble. All  agree  that  improvement  here,  Kke  the  original 
learning,  comes  largely  by  chance  successes.  One  hits 
upon  some  more  effective  combination  of  movements 
without  any  definite  foresight,  and  even  without  know- 
ing what  it  was  that  caused  the  improvement.  The 
worker  does  his  best  all  along,  and  at  times  an  improve- 
ment comes,  at  times  it  does  not.  There  is  always 
fluctuation  from  day  to  day.  This  seems  due  in  part 
to  the  general  physical  condition,  in  part  to  chance 
changes  in  the  character  of  the  work.  The  preliminary 
feeling  offers  little  or  no  indication  of  what  the  course 
of  the  work  is  to  be.  One  may  feel  well,  even  feel  cer- 
tain that  a  good  score  is  to  be  made  on  a  certain  day,  and 
find  that  the  accompHshment  is  lower  than  on  days  when 
the  general  feeHng  seems  to  offer  less  hope  of  success. 

Plateaus  in  Learning.  —  One  of  the  most  interesting 
questions  is  why  there  should  be  the  long  periods  of  no 
progress,  the  so-called  plateaus.  They  have  been  re- 
ported by  all  observers  and  are  present  in  most  of  the 
curves.  The  same  amount  of  effort  is  made,  and  all 
the  conditions  seem  to  be  approximately  the  same,  but 


THE    GENEILA.L   PRINCIPLES    OF   ACTION WILL       507 

no  progress  results  for  a  long  period.  Various  explana- 
tions are  given  for  them.  Bryan  and  Harter  assert 
that  they  are  periods  in  which  the  old  associations  or 
partial  habits  are  being  more  firmly  implanted,  and 
that  this  is  essential  for  any  further  advance.  In  cer- 
tain cases  this  seems  true.  It  has  also  been  asserted 
that  they  are  periods  in  which  the  worker  loses  interest 
and  relaxes  effort,  but  most  workers  do  not  accept  this 
as  a  general  explanation.  They  are  also  found  when 
effort  is  kept  at  a  maximum.  Granted  that  the  plateaus 
are  necessary  as  preparation  for  a  new  advance,  the 
reason  for  the  advance  to  a  new  level  offers  difficulties. 
Three  explanations  have  been  suggested,  (i)  The 
simplest  is  that  the  preparation  has  been  completed 
and  then  some  new  combination  of  movements  is  hit 
upon  that  makes  the  progress  possible.  (2)  Even 
Bryan,  who  argues  for  the  preparation  as  the  explana- 
tion of  the  plateau,  insists  that  there  is  often  at  least 
some  special  stimulus.  He  quotes  instances  of  teleg- 
raphers who  have  spent  some  time  in  a  small  office 
showing  a  sudden  rise  in  abihty  when  transferred  to  a 
main  hne  office.  Here  increase  is  probably  the  result  of 
new  incentives.  (3)  A  third  factor  that  plays  a  part 
is  becoming  clearly  aware  of  the  conditions  of  the  prob- 
lem, of  what  must  be  done  to  gain  full  control,  —  with 
that  there  is  frequently  an  increase  of  skill.  Effort  may 
play  a  part  or  may  not  according  to  the  time  at  which  it 
is  exerted.  If  all  is  ready,  increased  effort  may  give 
increased  effectiveness ;  if  the  effort  comes  too  soon,  it 
may  be  a  detriment  and  even  lead  to  postponement  of 
the  advance. 


5o8  FUNDAMENTALS    OF   PSYCHOLOGY 

Batson  has  recently  carried  out  an  investigation  of 
the  learning  process  for  tossing  balls.  His  conclusion 
is  that  the  plateaus  are  the  expression  of  the  time  taken 
to  associate  several  movements  into  a  chain  where 
several  separate  movements  must  be  combined  into  a 
unit  before  new  progress  is  possible.  Thus,  keeping 
two  balls  in  the  air  with  one  hand  requires  three  separate 
acts,  estimation  of  direction,  estimation  of  the  right 
height  to  throw  the  balls  or  of  the  force,  and  estimation 
of  the  time  required  for  the  balls  to  rise  and  fall,  since 
he  saw  a  ball  only  at  its  highest  point.  Unless  these 
three  acts  could  be  made  together,  no  real  progress  was 
possible.  The  plateaus  were  thought  to  correspond 
to  the  periods  during  which  the  three  factors  were  being 
combined,  or  during  which  each  was  being  learned 
separately  before  they  could  be  combined.  If  the  act 
to  be  learned  was  simple,  involved  only  one  process, 
no  plateaus  were  found.  If  attention  was  distributed 
over  the  entire  process,  if  one  included  all  three  part 
processes  in  attention  at  all  times,  the  plateaus  were 
not  so  likely  to  appear.  In  Batson's  experiments  they 
appeared  only  in  composite  acts  where  the  parts  were 
attended  to  separately  and  then  joined  into  groups. 
Whether  this  explanation  will  hold  for  all  problems 
can  be  determined  only  when  others  have  been  ana- 
lyzed into  their  parts  in  a  similar  way.  We  may  con- 
tent ourselves  here  with  the  statement  that  acquiring 
skill  in  complex  acts  is,  like  learning  in  the  simpler  forms, 
due  to  chance  trial  and  error,  a  process  in  which  the 
learner  does  not  know  how  he  makes  advances  either 
before  or  after  they  are  made.     The  associations  are 


THE    GENERAL   PRINXIPLES    OF    ACTION  —  WILL       509 

formed  through  frequent  repetition,  and  the  plateaus, 
or  stages  of  no  progress,  are  periods  when  associates 
necessar}^  to  new  progress  are  being  formed.  The  rise 
comes  through  some  chance  new  combination,  due  to 
some  new  incentive,  to  an  understanding  of  the  condi- 
tions of  the  advance,  or  merely  when  the  preHminary 
connections  have  been  sufficiently  thoroughly  developed. 
Learning  by  Imitation.  —  A  suggestion  that  may 
deserve  a  moment's  notice  is  that  one  may  learn  by 
imitation.  In  one  sense  this  is  of  course  very  largely 
true.  We  tend  to  imitate  the  more  striking  acts  of 
those  in  whom  we  are  interested  and  with  whom  we  come 
into  contact.  But  at  most  this  acts  as  a  goal  toward 
which  one  may  strive  by  a  process  of  trial  and  error, 
rather  than  as  an  immediate  cause  of  the  action.  That 
there  is  no  fundamental  impulse  to  imitate  is  e\ddent 
from  experiments  made  with  animals.  Thorndike  found 
that  when  one  cat  was  permitted  to  watch  another 
get  out  of  a  cage  a  number  of  times,  the  time  it  required 
to  make  the  same  movements  was  not  noticeably  short- 
ened. Similar  results  have  been  obtained  by  various 
other  investigators  under  approximately  the  same  condi- 
tions. In  his  work,  referred  to  above,  Bair  found 
that  even  compelling  the  muscle  to  make  the  movement 
to  be  learned  by  stimulating  it  by  an  induction  current 
did  not  decrease  the  time  required.  The  impulse  must 
develop  from  the  cue  or  stimulus  to  be  used  to  incite 
the  movement,  if  learning  is  to  take  place.  To  be  helped 
serves  at  most  to  direct  attention  to  the  right  movement, 
but  to  make  it,  if  it  be  not  already  learned,  requires  the 
usual  process  of  trial  and  error.     The  same  statement 


5IO  FUNDAMENTALS    OF    PSYCHOLOGY 

may  be  made  of  the  effect  of  imitation  in  more  complex 
acts  that  are  already  at  command.  The  sight  of  another 
making  them  serves  to  give  the  idea,  and  that  may,  if 
desired,  lead  to  the  act.  What  force  it  has  is  due  to 
the  general  social  instincts,  rather  than  to  any  specific 
instinct  or  impulse  to  imitate. 

Consciousness  and  Movement.  —  When  one  attempts 
to  determine  the  factors  that  precede  and  control  move- 
ments already  learned,  to  ask  why  the  movement  is 
made  and  how  it  is  controlled,  one  comes  upon  rather 
more  difference  of  opinion.  We  have  already  seen 
that  all  movement  follows  upon  stimulation.  These 
stimulations  all  go  back  in  last  analysis  to  sensory  excita- 
tion. In  most  of  the  more  elaborate  acts  of  human 
adults,  some  consciousness  accompanies  this  excitation, 
and  in  a  very  large  number  of  cases  the  excitation  that 
precedes  is  from  the  activity  of  a  memory  tract  rather 
than  from  the  stimulation  of  a  sense  organ  directly. 
Each  of  these  factors  introduces  certain  compHcations, 
raises  questions  that  must  be  discussed.  One  of  the 
first  is  what  does  consciousness  add  to  the  process  and 
is  it  necessary  that  consciousness  should  be  present? 
Here  opinions  differ.  Consciousness  does  accompany 
many  if  not  most  acts  when  they  are  first  made.  On  the 
other  hand,  before  an  act  has  been  definitely  learned, 
consciousness  of  what  is  to  be  done  seems,  as  has  been 
said,  to  help  very  little  in  the  learning ;  after  it  has  been 
learned,  consciousness  becomes  more  and  more  indefinite 
until  finally  it  may  completely  disappear.  In  view  of 
these  facts  it  seems  difficult  to  do  more  than  insist  on 
the  importance  of  the  sensory  innervation  as  universally 


THE    GENERAL   PRINCIPLES    OE   ACTION  —  WILL       511 


oeact; 


present.  The  degree  of  consc^^Jfess  and  what  its 
effect  upon  movement  is  may  be  left  an  open  question, 
and  its  presence  need  be  pointed  out  only  where  what  is 
conscious  gives  a  definite  explanation  of  the  character- 
istics of  the  act. 

The  Incentives  to  Movement.  —  We  may  di\dde  the 
conscious  accompaniitients  of  movements  into  three 
groups.  First,  the  initiating  processes;  secondly,  the 
directly  sensory  processes ;  third,  the  awareness  of  the 
result.  These  must  be  considered  separately.  WTiat 
the  initiating  process  may  be  has  been  much  dis- 
cussed and  many  suggestions  have  been  made  concern- 
ing it.  Probably  all  have  been  too  definite.  Thus, 
several  have  inclined  to  the  view  that  movement  must 
be  preceded  by  the  kinaesthetic  sensation  that  arises 
when  the  movement  is  made.  To  speak  a  word  one 
must  recall  the  sensations  made  when  that  word  has 
been  uttered  at  some  earlier  time,  or  to  move  the  hand 
to  cut  the  leaf  of  a  book  one  is  reading,  one  must  recall 
the  sensations  felt  when  that  movement  was  made. 
Woodworth  has  shown  that  these  sensations  are  seldom 
present,  and  a  Httle  observation  will  indicate  that  you 
do  not  ordinarily  have  them  in  mind  before  the  move- 
ment is  made.  More  frequently  present  are  \dsual 
images,  but  even  these  are  not  always  definite.  If  you 
decide  to  rise  and  walk  across  the  room,  you  will  see 
that  all  that  is  necessary  is  to  notice  the  book  and  re- 
member that  you  must  read  something  in  it  before  you 
go  on.  With  a  very  general  idea  and  the  sight  of  the 
book,  the  movement  begins  and  is  carried  to  its  conclu- 
sion.    Even  visual  images  are  not  always  present.     This 


512  FUNDAMENTALS    OF   PSYCHOLOGY 

is  too  obvious  to  id^jron  in  the  case  of  speech,  which 
is  influenced  nx)re  by  auditory  images.  In  most  cases 
the  imagery  that  precedes,  whose  presence  may  be  re- 
garded as  constituting  the  intention  to  move,  is  very 
schematic  and  almost  anything  in  any  way  related  to 
the  act  may  serve  as  the  incentive  to  movement. 

Meaning  as  an  Incentive.  —  In  this,  action  is  very  little 
different  from  thought.  In  fact,  Woodworth  first  came 
to  his  hypothesis  of  imageless  thought  through  a  study 
of  the  mental  content  that  precedes  action.  As  in 
thinking,  our  memories  and  ideas  are  brought  into  sys- 
tematic groups,  in  which  any  one  element  may  serve  to 
represent  any  other,  so  the  antecedents  of  acts  are  also 
grouped  and  the  act  results  from  the  appearance  of  any 
element  of  the  system.  Organization  is  as  evident  in 
the  control  of  action  as  in  the  control  of  thought.  Just 
as  an  idea  which  is  not  at  all  similar  to  an  object  may 
represent  that  object,  so  an  idea  or  sensation  that  has 
been  only  indirectly  associated  with  a  movement  may 
come  to  represent  that  movement  and  in  fact  constitute 
the  intention  to  make  it.  In  practice  one  finds  that 
almost  any  idea  or  impression  that  has  been  connected 
with  an  act  may  be  the  immediate  predecessor  of  that 
act.  Any  mental  process  may  constitute  the  incentive 
to  any  act  with  which  it  has  been  closely  associated, 
just  as  any  image  may  have  any  idea  with  which  it  has 
been  associated  as  its  meaning.  Colloquial  language 
connects  the  two  and  uses  the  single  word  for  both.  *  I 
mean  to  do  that '  is  a  common  expression  as  the  equiv- 
alent of  '  I  intended  to  do  that '  and  the  use  of  the  term 
is  justified  by  psychological  analysis.     A  meaning,  using 


THE    GENERAL    PRINXIPLES    OF   ACTION  —  WILL       ^It 

the  terms  in  the  technical  sense  eC^he  earlier  chapters, 
may  quite  as  naturally  have  an  issue  in  movement  as 
stop  short  in  the  mere  representation  of  an  idea. 

Different  Types  of  Antecedents  of  Movements.  — 
Three  distinct  classes  of  mental  processes  may  be  dis- 
covered among  the  antecedents  of  action.  The  most 
common  is  the  intention  or  the  meaning,  a  representa- 
tion in  some  form  of  the  goal  or  result  of  the  act.  This 
goal  may  be  represented  as  a  concrete  sensation,  as  a 
very  general  notion,  or  may  have  no  appreciable  imagery, 
or  at  least  no  appreciated  imagery.  It  may  take  any 
of  the  forms  of  a  concept.  The  initiating  idea  for  a 
stroke  at  golf  may  be  a  definite  image  of  the  point  where 
the  ball  is  to  land,  it  may  be  some  vague  verbal  thought 
that  it  is  well  to  land  near  the  tree  on  this  hole,  or  it 
may  be  that  the  stroke  is  guided  by  nothing  more  defi- 
nite than  the  assumption  that  the  next  stroke  is  in  that 
general  direction,  an  assumption  that  is  not  formulated 
but  is  due  to  the  appreciation  of  a  particular  step  in  the 
game.  It  must  be  said  that  this  third  stage  is  very  rare 
in  a  game  of  skill,  but  much  more  frequent  in  partially 
automatized  tasks.  At  times,  intention  is  lacking  or 
much  in  the  background,  and  a  sensation  or  idea  closely 
associated  with  the  movement  serves  as  the  incentive. 
This  may  be  either  the  kinaesthetic  image  mentioned 
above,  or  it  may  be  the  sight  of  an  object,  as  when  a  spot 
on  the  tablecloth  catches  the  eye,  and  the  finger  moves 
towards  it  even  to  the  later  embarrassment  of  guest 
and  hostess.  The  second  cue  is  different  from  the  first 
in  that  it  does  not  correspond  to  a  purpose,  or  may  be 
directly    opposed    to    the    general    purpose.     Finally, 


514  FUNDAMENTALS    OF    PSYCHOLOGY 

some  sensory  stimulus  may  cause  a  movement  that  is 
altogether  unrelated  to  the  intention  of  the  moment. 

Interaction  of  Incentives.  —  These  three  different 
sorts  of  antecedents  may  oppose  and  disturb  each  other 
in  the  control  of  the  resulting  movement.  The  intention 
is  the  most  frequent  antecedent  but,  if  at  any  point  in 
carrying  out  the  intention  an  extraneous  idea  be  per- 
mitted to  become  dominant  in  consciousness,  it  disturbs 
or  prevents  the  movement.  Thus,  if  one  is  making  a 
golf  stroke  and  suddenly  permits  the  ditch  immediately 
in  front  to  catch  attention,  the  ball  goes  into  the  ditch 
in  spite  of  the  good  general  intentions  of  the  player.  In 
a  baseball  game,  in  the  same  way,  if  some  object  other 
than  the  point  at  which  the  ball  should  be  thrown  is 
attended  to,  a  bad  play  is  fairly  certain  to  result.  Even 
the  attachment  of  a  not  to  an  idea  does  not  always  pre- 
vent it  from  affecting  the  act.  Langfeld  found  that 
in  experiments  which  consisted  in  moving  a  wire  along 
a  groove,  endeavoring  to  avoid  touching  the  sides,  the 
experimenters  were  more  likely  to  touch  the  edge  if  he 
asked  them  not  to  touch  it  than  if  he  told  them  to  keep 
the  wire  in  the  middle  of  the  groove.  Attention  to  the 
side  induced  a  movement  toward  it  in  spite  of  the  inten- 
tion to  avoid  it.  Within  limits,  trying  not  to  do  a  thing 
has  the  same  effect  as  trying  to  do  it.-  This  is  partic- 
ularly true  in  acts  of  skill  and  of  movements  only  partly 
learned.  It  is  true  in  general  that  an  intention  of  the 
more  remote  sort  is  frequently  conquered  by  an  idea 
of  a  specific  movement,  even  if  that  be  directly  contrary 
to  the  intention.  The  same  holds  of  the  third  type  of 
antecedent,  a  sensation  not  directly  connected  with  the 


THE    GENERAL   PRINCIPLES    OF   ACTION — WILL      515 

movement.  A  sudden  stimulus  that  comes  in  the  course 
of  an  attempt  to  make  a  difficult  movement  will  fre- 
quently disturb  or  destroy  it.  A  sudden  loud  noise  or 
bright  light  spoils  a  delicate"  line  with  the  pen  or  the  aim 
of  a  rifle  or  a  drive  at  golf.  Not  the  meaning  alone 
but  that,  together  with  the  idea  or  object  that  holds 
attention  or  the  sensory  stimulus  that  forces  its  way 
into  consciousness,  serves  to  direct  the  movement. 

The  Control  of  Movements.  —  The  second  of  the 
three  groups  of  conscious  states  accompanying  move- 
ment is  the  sensations  aroused  by  the  movement. 
These  also  play  an  important  part  in  directing  the  act. 
Movement  is  in  this  respect  much  like  memory  or  reason- 
ing or  the  process  of  learning.  The  incentive  must  be 
distinguished  from  the  control ;  the  attempt,  from  the 
recognition  of  success  or  failure,  together  with  the  correc- 
tion that  goes  with  the  latter.  In  addition  to  the  sen- 
sory processes  that  initiate  the  movement,  the  accom- 
pan>dng  sensations  exercise  a  constant  guidance.  These 
are  divided  by  James  into  two  classes,  the  resident  and 
remote  sensations.  The  resident  are  the  kinassthetic 
sensations.  The  remote  are  the  sensations  from  eye 
or  ear  that  indicate  where  the  moving  member  is  or  what 
the  sound  is  that  is  being  produced.  Both  of  these 
sensations  or  groups  of  sensations  ordinarily  control 
the  movement  without  being  directly  noticed.  As  a 
finger  is  moved  with  the  eyes  closed,  the  kinassthetic 
sensations  are  constantly  coming  to  the  cortex  and  send- 
ing out  reflexes  that  serve  properly  to  direct  the  move- 
ment to  graduate  its  force  and  extent.  They  are  most 
easily   demonstrated  by   their  absence.     In   tabes   the 


5l6  FUNDAMENTALS    OF   PSYCHOLOGY 

motor  nerves  are  unimpaired,  but  the  posterior  columns 
in  the  cord  which  carry  the  kinaesthetic  sensations  are 
destroyed.  A  characteristic  symptom  of  the  disease 
is  inability  to  control  the  movements.  When  the  eyes 
are  closed,  the  patient  is  not  able  to  bring  thumb  and 
finger  together  accurately  and  still  less  to  bring  two 
fingers  together  in  front  of  the  face  with  a  single  sweep. 
Locomotor  ataxia  with  its  irregular  gait  is  one  form  of  the 
disease. 

Remote  Sensations.  —  The  remote  sensations  are 
also  active  in  detecting  and  correcting  any  departures 
from  the  intended  course  of  action.  Thus,  when  writ- 
ing, if  the  hand  starts  to  make  a  crooked  line,  it  is  at 
once  seen  and  the  eye  directs  it  back  to  the  right  posi- 
tion. The  influence  of  the  eye  is  not  appreciated  but, 
if  one  attempts  to  write  with  the  eyes  closed,  it  is  at 
once  apparent  that  an  important  correcting  force  is 
lacking.  The  ear  acts  in  the  same  way  in  governing 
speech,  and  the  tone  in  singing.  Experiments  show  that 
most  singers,  some  of  them  among  the  most  famous, 
are  not  able  to  strike  the  correct  tone  at  once,  but  make 
an  attempt,  are  quick  to  detect  that  the  tone  is  too  high  or 
too  low,  and  so  adjust  the  pitch  to  the  correct  one.  The 
violinist,  too,  does  not  estimate  the  position  of  his  fingers 
on  the  string  by  the  kinaesthetic  sensations,  an  esti- 
mation that  would  require  marvellous  accuracy,  but 
approximates  the  position  first,  and  then,  as  the  bow 
begins  to  give  the  tone,  he  adjusts  the  length  of  the 
string  until  his  ear  tells  him  that  the  tone  is  correct. 
That  the  remote  sensation  is  essential  is  shown  by  the 
fact  that  the  deaf  cannot  speak  without  special  train- 


THE    GENERAL   PRINCIPLES    OF   ACTION  —  WILL      517 

ing.  This  seems  to  supply  the  control  that  the  ear 
cannot  give  by  kinaesthetic  and  tactual  sensations. 
The  deaf  child  feels  the  teacher's  vocal  organs  and  keeps 
trying  until  he  makes  his  own  carry  out  the  same  move- 
ments. The  sameness  of  movement  is  at  first  recog- 
nized by  touch,  but  with  practice  the  kinaesthetic 
sensations  may  be  substituted.  These  control  processes 
also  become  automatic,  so  that  one  notices  neither 
the  sensations  themselves  nor  the  fact  that  they  exer- 
cise control.  The  sensations  from  the  eye  guide  the 
hand  reflexly,  or  with  as  little  thought  as  is  required 
for  the  reflex. 

Another  striking  case  of  reflex  guidance  of  this  sort 
is  that  exerted  by  the  static  sense,  the  stimuli  from 
the  vestibular  branch  of  the  auditory  nerve.  This, 
as  was  seen  in  the  earlier  chapters,  makes  close  connec- 
tions with  the  motor  centres  in  the  brain  stem,  par- 
ticularly with  the  cerebellum  and  the  roots  of  the 
motor  oculi  nerves.  These  sensory  nerves  probably  give 
no  sensations,  but  nevertheless  they  guide  the  move- 
ments of  the  body  as  a  whole,  serve  to  keep  the  balance, 
give  rise  to  compensatory  eye  movements,  —  movements 
that  keep  the  eyes  fixed  on  the  same  point  in  spite  of 
the  movements  of  the  head  and  body.  The  sensory 
impulse  calls  out  these  movements  continuously  and 
with  no  knowledge  that  the  movement  has  been  made, 
certainly  with  no  appreciation  of  the  fact  that  they 
are  producing  the  movements.  The  stream  of  impulses 
coming  in  through  the  vestibular  nerves  constitutes 
an  important  element  in  the  forces  that  control  any 
movement. 


5l8  FUNDAMENTALS    OF   PSYCHOLOGY 

Any  act,  then,  may  be  said  to  be  the  outcome  of 
the  appreciation  of  a  situation  that  requires  movement. 
The  immediate  incentive  is  usually  some  object  or  idea 
that  for  the  moment  holds  the  centre  of  attention. 
But  this  incentive  is  nearly  always  not  the  picture  of 
the  movement  to  be  made ;  it  is  more  frequently  some 
idea  of  the  end  to  be  accomplished.  If  the  movement 
is  relatively  unfamiliar,  it  is  an  idea  of  sorde  immediate 
act;  if  very  familiar,  it  is  usually  the  remote  end  that 
is  held  in  mind.  The  intention  does  no  more  than 
mean  the  movement ;  it  seldom  recalls  it  in  sensory 
terms.  Always  the  movement  is  guided  by  the  resi- 
dent and  remote  sensations.  These  adjust  it  to  the 
conditions  of  the  moment.  When  a  movement  has  been 
repeated  sufhciently  often  to  become  automatic,  atten- 
tion is  needed  only  at  the  beginning.  The  act  is  started, 
and  attention  then  turns  to  something  else ;  the  asso- 
ciation between  the  movements  and  the  resident  and 
remote  sensations  serves  to  carry  it  to  its  goal.  Thus, 
in  walking  on  a  familiar  course,  one  merely  decides 
to  go  to  a  certain  place  and,  when  once  started,  one 
step  starts  the  next,  always  under  the  control  of  the 
remote  and  resident  sensations.  The  visual  stimuli 
lead  to  the  avoidance  of  obstacles,  guide  in  making 
the  necessary  turns  and,  unless  some  new  obstacle  is 
encountered,  one  may  go  into  a  brown  study  at  the 
moment  of  starting  and  not  realize  again  what  is  going 
on  about  until  the  destination  has  been  reached.  All 
movements  or  chains  of  movements,  at  first  learned  or 
joined  together  by  effort  and  under  the  influence  of  a 
complete   consciousness,   tend   gradually   to   lose   more 


THE    GENERAL   PRINCIPLES    OF   ACTION  —  WILL      519 

and  more  of  the  conscious  accompaniments  and  ante- 
cedents. Finally,  in  more  complex  acts,  they  may  start 
from  some  unnoticed  stimulus  ;  in  the  case  of  simple  acts 
or  a  number  of  unified  simple  movements,  they  may  be 
started  by  a  single  idea,  may  be  initiated  by  a  conscious 
process  and  guided  to  their  end  by  habit  without  further 
consciousness.  Associations  between  the  movements 
themselves  or  between  the  resident  sensations  of  one 
movement  and  the  motor  processes  required  for  the 
next  take  the  place  of  all  more  definite  awareness. 
Even  in  these  automatic  acts,  there  is  guidance  by  a 
wide  group  of  habitual  connections  between  neurones, 
not  at  all  appreciated  by  the  agent. 

Choice  and  Motives.  —  We  have  been  assuming  all 
through  that  the  intention  to  make  a  movement  has 
been  present,  but  a  process  antecedent  to  the  inten- 
tion requires  discussion.  This  is  the  problem  of  choice. 
It  is  true  that  most  acts  are  automatic  or  habitual, 
that  the  decision  was  determined  long  before  the  time 
the  act  is  to  be  performed,  and,  when  the  occasion  pre- 
sents itself,  is  carried  out  immediately.  But  in  occa- 
sional instances  two  opposed  acts  are  felt  to  be  possible, 
and  it  is  necessary  to  choose  which  is  to  be  made. 
The  actual  act  of  choice  is  relatively  simple.  It  is 
constituted  in  giving  one  intention  free  play  and  in 
checking  the  others.  The  actual  mental  content  con- 
sists in  attending  to  the  movement  to  be  made  or  the 
result  to  be  attained.  When  the  choice  or  decision  is 
made  long  before  it  is  to  be  carried  into  effect,  it  consists 
frequently  in  outlining  the  course  of  action  in  words 
or    in    some    idea,  —  some    concept    perhaps.     When 


520  FUNDAMENTALS    OF   PSYCHOLOGY 

the  time  comes,  the  stimuli  present  lead  at  once  to  the 
act.  The  only  new  problem  in  connection  with  choice 
is  what  leads  to  the  intention,  why  one  course  is  chosen 
rather  than  any  other.  This  goes  back  to  the  deter- 
mination of  the  selection  of  one  or  the  other  end,  or  of 
one  or  another  of  the  possible  sensations  that  are  present 
in  consciousness.  In  either  case  the  explanation  Kes 
finally  in  the  laws  of  attention  and  association,  and 
offers  Httle  that  is  new.  The  deciding  factors  are  sub- 
jective, those  that  have  been  seen  to  be  the  conditions 
of  attention  and  of  association.  One  seldom  regards  as 
choice  the  decision  determined  by  objective  factors  alone. 
Mental  Attitude  in  Control  of  Choice.  —  The  influence 
of  the  situation  and  the  mental  setting  or  context  have 
been  frequently  mentioned  above.  It  was  brought  out 
in  a  slightly  different  form  by  Ach  ^  in  a  long  investiga- 
tion of  the  conditions  of  choice  by  means  of  the  reac- 
tion experiment.  First  he  asked  his  subjects  to  move 
the  right  finger  when  a  letter  E  was  shown,  and  the 
left  when  the  letter  0.  The  times  required  for  making 
each  movement  were  measured.  It  was  found  that 
there  was  no  real  decision  made  after  the  cards  were 
shown,  but  that  the  movements  were  made  at  once 
because  of  the  previous  prepa-ration.  Wlien  the  sub- 
ject was  left  free  to  react  with  either  finger,  it  was  found 
that  more  time  was  taken  than  when  the  finger  to  be 
moved  was  prescribed.  These  facts  may  be  regarded 
as  indicating  that  the  first  form  of  reaction  gives  play 
to  choice,  while  the  others  were  determined  by  the  condi- 
tions of  the  experiment,  the  purpose  of  the  moment. 

^  Ueber  die  Willenstatigkeit  und  das  Denken. 


THE    GENERAL   PRINCIPLES    OF   ACTION — WILL       52 1 

It  was  in  these  same  experiments  that  the  centre  1  of 
the  arithmetical  associations  was  studied.  The  same 
results  were  obtained.  When  two  numbers  were  shown 
one  above  the  other  and  the  observer  was  told  in  ad- 
vance to  add  or  subtract,  the  result  came  at  once  or 
after  a  relatively  short  time.  When,  on  the  other  hand, 
the  numbers  were  shown  with  no  instructions,  the  result- 
ing process  was  much  delayed,  and  the  observer  had  a 
chance  to  study  the  process  of  choice.  This  task  or 
purpose  serves  to  control  choice  just  as  it  does  to  deter- 
mine association.  The  efTect  of  the  purpose  is  replaced 
by  the  situation  and  the  general  intentions  of  the  mo- 
ment in  many  choices  of  everyday  life.  It  is  this  that 
leads  one  to  take  an  umbrella  when  the  sky  is  cloudy 
and  a  cane  when  it  is  clear  as  one  goes  past  the  rack 
in  the  hall,  to  choose  a  serious  volume  when  one  com.es 
into  the  study  in  working  hours  and  a  novel  or  the  news- 
paper in  the  period  just  after  dinner.  In  all  these  things 
the  choice,  while  apparently  undetermined,  is  guided  by 
the  general  attitude  and  the  en\dronment. 

More  Remote  Influences  in  Choice.  —  In  more  com- 
plicated and  important  instances  of  choice,  the  final 
selection  is  similarly  determined,  but  the  controlUng 
influences  are  much  more  numerous.  The  final  release 
comes  with  thinking  of  the  end  to  be  accomplished 
with  the  full  behef  that  the  act  is  to  be  carried  out.  The 
antecedent  processes  are  much  Hke  the  balancing  of 
decisions  in  doubt  before  full  belief  presents  itself. 
One  thinks  first  of  one  alternative,  then  of  the  other. 
After  these  alternations  have  repeated  themselves 
several  times,  one  finally  dominates,  is  held  in  mind, 


522  FUNDAMENTALS    OF    PSYCHOLOGY 

and  the  others  are  by  that  very  fact  excluded  ;  the  deci- 
sion is  made.  The  forces  that  favor  the  possible  alterna- 
tives are  to  be  found  in  the  instincts  on  the  one  side  and 
the  social  forces  on  the  other.  They  constitute  what 
are  called  the  motives.  The  motives  are  themselves 
pretty  well  out  of  consciousness  ordinarily.  One  knows 
only  that  one  course  of  action  or  another  is  preferable 
but  has  no  knowledge  why  it  is  preferred.  Carrying 
this  back,  we  see  that  of  the  possible  hues  of  conduct 
the  one  is  chosen  which  proves  most  attractive.  Why 
it  is  attractive  is  determined  by  natural  endowment 
and  education.  There  is  no  trace  of  what  is  ordinarily 
called  will. 

Is  there  a  Peculiar  Will  Element?  —  A  problem  much 
discussed  since  the  beginning  of  psychological  theory  is 
whether  there  is  a  specific  quahty  or  a  specific  function, 
apart  from  those  outKned  above,  which  can  be  called 
the  will.  The  earher  writers,  always  tending  to  dis- 
cover a  separate  faculty  or  force  for  each  of  the  words 
in  common  use,  hardly  questioned  the  existence  of 
something  of  the  kind,  something  which  was  an  actual 
force  in  decisions  and  an  incentive  to  action.  As  the 
direct  examination  of  mental  states  began  to  take  the 
place  of  speculation  with  only  inaccurate  observation, 
fewer  and  fewer  men  were  able  to  discover  this  peculiar 
state.  Instead,  an  ever-increasing  number  of  authorities 
found  the  final  cause  of  action  in  an  idea  that  was 
attended  to,  in  an  idea  of  movement  with  the  belief 
that  it  was  to  take  place,  or  in  the  feeling  qualities  pre- 
ceding or  accompanying  the  idea.  The  more  work 
done  upon  the  analysis  of  the  consciousness  preceding 


THE    GENERAL   PRINCIPLES    OF   ACTION  —  WILL       523 

action,  the  less  there  was  found  that  was  peculiar  to 
this  state. 

Recently  two  investigators,  Ach  and  Michotte  and 
his  followers,  have  revived  the  old  doctrine  in  a  slightly 
new  form.  In  certain  of  his  more  compKcated  reaction 
time  experiments,  Ach  asserts  that  it  is  not  merely 
holding  the  idea  of  the  movement  in  the  centre  of  con- 
sciousness, but  that  in  addition  to  this  it  is  necessary 
that  the  self  becomes  momentarily  identified  with  the 
movement  to  be  made.  At  the  moment  the  self  is  thus 
identified  with  the  one  alternative,  the  choice  is  made, 
the  action  is  determined.  A  somewhat  similar  state- 
ment is  made  by  Michotte  in  connection  with  a  choice 
between  operations  upon  numbers  as  a  result  of  experi- 
ments carried  on  by  himself  and  Priim.^  In  a  second  ex- 
periment, also  on  reaction  times,  conducted  with  Barrett,^ 
measurements  were  made  of  the  time  between  being 
offered  two  Hquids,  and  choosing  and  swallowing  one 
of  them.  The  liquids  represented  different  degrees 
of  pleasantness  and  unpleasantness.  They  were  tested 
in  advance  and  designated  by  letters  that  should  have 
no  associations  other  than  those  which  developed  during 
the  experiment.  The  observer  was  to  watch  carefully 
what  preceded  the  decision  and  to  determine  if  possible 
what  was  the  deciding  factor  in  his  choice.  In  this 
series  of  experiments  the  element  of  voluntary  choice 
seemed  to  play  a  smaller  part.     In  fact,  Barrett  regards 


^  Michotte  and  Priim,  Etude  experimentale  sur  le  choix  volon- 
taire  et  ses  antecedentes  immediats,  Archives  de  psychologic,  vol. 
X,  p.  113. 

^  Barrett,  Motivation  Tracts  and  Motivation  Forces. 


524  FUNDAMENTALS    OF   PSYCHOLOGY 

the  result  as  proof  that  choice  is  made  and  executed 
without  any  pecuKar  new  activity  that  could  be  desig- 
nated an  act  of  volition.  Instead,  he  found  that  one 
arranged  the  tastes  as  they  were  learned  in  order  of 
agreeableness,  and,  when  they  were  presented,  the  value 
on  this  scale  was  an  immediate  guide  to  the  choice. 
The  whole  choice  was  completed  when  the  Hquid  had 
been  given  its  letter  and  place  in  the  series.  He  finds 
that  the  determinants  of  the  act  are  approximately  the 
same  as  those  we  have  enumerated  above.  Michotte^ 
in  reply  reasserts  his  belief  in  a  pure  act  of  voHtion 
which  must  intervene  in  all  acts  of  choice,  whether 
related  to  action  or  not,  and  after  the  choice  is  made 
must  again  intervene  in  the  execution  of  the  act  involved 
in  the  choice.  He  believes  that  the  selection  of  one  from 
a  group  of  liquids  of  known  value  tends  to  render  the 
process  more  automatic  and  that  this  accounts  for  the 
smaller  part  played  by  voluntary  choice. 

This  difference  of  opinion  between  Barrett  and  Mi- 
chotte  is  typical  of  the  opposing  possibilities  in  the 
explanation  of  a  voluntary  act.  On  the  one  hand, 
emphasis  is  placed  upon  the  more  remote  underlying 
conditions ;  on  the  other,  upon  the  necessity  for  dis- 
criminating between  the  alternatives  for  holding  in 
mind,  first  one  of  the  motives,  and  then  the  other,  and 
making  a  positive  choice  between  them.  On  Barrett's 
interpretation,  the  motives  are  effective  because  they 
appeal  to  certain  instinctive  or  habitual  and  social 
traits  in  the  man's  nature.    On  Michotte's,  the  final 

^  Michotte,  Apropos  de  contributions  rccentes  a  la  psychologie  de 
la  volonte,  Ann.  de  L'Institute  Super,  dc  Phil.,  No.  ix. 


THE    GENERAL  PRINCIPLES    OF   ACTION WILL      525 

determinant  of  action  is  a  force  or  active  element  which 
serves  to  make  the  choice  and  release  the  act.  On  the 
second  alternative,  the  active  element  is  hard  to  de- 
scribe, is  found  by  only  a  few  men  and  by  them  only  on 
rare  occasions.  Popularly,  it  plays  a  large  part  in  dis- 
cussions, but  the  observation  by  the  untrained  men 
upon  which  it  rests  is  faulty  and  much  of  the  feeling  of 
will  which  it  observes  is  made  up  of  strain  sensations, 
which  even  Michotte  would  not  regard  as  an  essential 
part  of  his  voluntary  act.  Viewed  from  the  practical 
point,  it  makes  very  Kttle  difference  whether  this  active 
element  is  or  is  not  assumed.  All  would  agree  that 
when  will  acts,  it  acts  in  the  light  of  the  motives ;  it 
is  an  expression  of  the  nature  of  the  man,  and  that 
in  turn  is  dependent  upon  his  instincts  and  training, 
his  immediate  purposes  and  general  ideals.  The  only 
question  remaining  is  whether  these  act  directly  in  the 
execution  of  the  movement,  or  whether  they  act  first 
upon  the  will  and  that  in  turn  determines  the  act.  In 
consideration  of  the  uncertainty  as  to  whether  the  will 
activity  exists  and  what  it  is  Hke  if  it  exists,  it  seems 
more  simple  and  safer  to  omit  it  as  superfluous,  and  to 
assume  that  the  observed  conditions  determine  action 
directly.  On  that  conclusion, '  will '  is  a  term  to  designate 
the  whole  man  active,  or  a  word  used  to  distinguish  be- 
tween the  acts  that  imply  choice  and  are  controlled  by 
the  system  of  purposes  as  opposed  to  the  automatic  acts, 
not  a  word  to  designate  any  new  and  distinct  entity. 

The  Will  and  Freedom.  —  This  result  suggests  the 
old  problem  of  the  freedom  of  the  will,  and  it  may  be 
considered  here,  in  spite  of  the  fact  that  it  is  at  present 


526  FUNDAMENTALS    OF    PSYCHOLOGY 

regarded  as  belonging  to  ethics  rather  than  to  psychology. 
At  first  sight  it  seems  a  logical  inference  that,  if  man  has 
no  will,  it  cannot  be  free.  This  defines  the  will  too 
narrowly;  it  would  restrict  it  to  the  something  that 
we  could  not  find  standing  between  the  motives  and  the 
act  itself.  If  we  regard  the  will  as  the  sum  of  the  condi- 
tions which  lead  to  action  or  to  spontaneous  action,  or 
even  more  generally  as  the  whole  man  active,  the  ques- 
tion cannot  be  disposed  of  so  summarily.  From  this 
point  of  view,  the  answer  as  to  whether  the  man  is  free 
depends  very  largely  upon  how  we  define  'the  man.'  We 
have  seen  throughout  that  many  of  the  determinants 
of  all  mental  action,  and  particularly  of  voluntary 
action,  are  to  be  found  in  his  instincts,  in  the  way  he 
has  been  affected  by  education  and  by  the  society  in 
which  he  has  lived,  by  his  nature  and  nurture  in  the 
broadest  use  of  both  terms.  If  one  is  to  oppose  these 
external  forces  to  the  man  himself,  a  good  case  could 
be  made  for  the  statement  that  the  man  is  largely 
determined  by  forces  outside  of  himself.  But  if  one 
make  the  division  between  the  man  and  all  of  these 
factors,  if  one  take  away  from  the  man  all  that  he  has 
learned,  all  the  controlling  forces  of  society,  and  all 
of  his  natural  endowments,  his  instincts  and  innate 
tendencies,  only  a  rag  of  a  man  would  be  left ;  most 
that  is  peculiarly  himself  would  have  disappeared. 
It  is  altogether  more  satisfactory  and  truer  to  the  facts 
to  regard  these  influences  as  included  in  the  man,  to 
think  of  him  as  in  part  at  least  the  product  of  his  heredity 
and  environment,  for  this  is  the  man  as  we  know  him. 
To  attempt  to  divide  the  controlling  forces  into  two 


THE    GENERAL    PRINCIPLES    OF    ACTION  —  WILL       527 

groups,  one  external,  the  other  internal,  one  environ- 
mental, the  other  personal,  has  never  been  attempted, 
and  no  two  men  agree  where  the  di\dsion  would  come. 
Oppose  the  man  as  he  is  to  external  forces  and  he  must 
be  said  to  control  his  own  acts.  They  are  the  expression 
of  the  whole  man,  and  he  is  free  to  do  as  he  chooses. 
One  may  put  the  solution  of  the  problem  in  another 
way  by  asserting  that  man  is  free  to  do  what  he  desires, 
but  his  desires  are  the  outcome  of  his  instincts  and 
en^dronment  and  over  these  he  has  Httle  control.  In 
other  words,  the  question  is  largely  one  of  classifying 
facts  and  of  defining  terms.  The  facts  themselves 
are  largely  accepted  by  all. 

In  practice,  acceptance  of  one  theory  or  the  other 
makes  Httle  difference.  What  one  generally  does  is  to 
think  of  one's  self  as  a  free  agent  in  every  respect  and 
of  every  one  else  as  rigidly  determined  by  environment 
and  education.  It  is  only  when  one  takes  the  objec- 
tive attitude  toward  one's  own  acts,  that  one  tries  to 
trace  them  to  their  conditions.  Probably  this  assump- 
tion works  best  in  practice.  The  new  tendency  to 
regard  man  as  the  product  of  his  environment  has  led 
to  the  improvement  in  social  conditions,  to  the  recogni- 
tion that  mankind  in  the  mass  may  be  improved  if  one 
will  but  begin  with  remedying  the  fundamental  condi- 
tions of  living,  that  changing  his  environment  is  better 
than  talking  to  him.  Improvements  in  education,  in 
housing  conditions,  and  all  the  multitude  of  laws  for 
bettering  the  environment  of  the  poor,  are  due  to  the 
growing  tendency  to  regard  the  en\ironment  as  respon- 
sible for  the  actions  of  others.     On  the  other  hand,  the 


528  FUNDAMENTALS    OF   PSYCHOLOGY 

belief  in  one's  own  freedom  probably  gives  added  initia- 
tive, and  increased  recognition  of  individual  responsi- 
bility that  would  be  lost  were  one  to  think  of  one's  self 
as  a  mere  link  in  the  world  chain.  However,  the  in- 
stinct of  self-assertion  is  too  strongly  embedded  to 
permit  acceptance  of  any  theory  to  change  the  aggres- 
sive individual  into  an  inert  one. 

Probably  the  difference  in  the  attitude  towards  crime 
and  the  criminal  more  clearly  represents  the  effects  of 
the  two  theories.  On  the  older,  free-will  doctrine,  the 
criminal  was  altogether  responsible  for  his  acts.  He 
would  or  he  would  not  carry  out  each  act.  There  could 
be  no  control  of  crime,  because  no  one  could  tell  when 
an  individual  might  decide  to  commit  one.  The  other 
theory  looks  upon  the  criminal  as  the  product  of  his 
heredity  and  of  his  environment,  in  much  the  same  way 
that  a  sick  man  is  the  victim  of  circumstances.  In  the 
extreme  form,  the  whole  problem  is  one  of  removing  the 
causes  of  the  crime,  as  the  control  of  health  is  one  of 
removing  the  causes  of  disease.  The  attitude  toward 
punishment  changes  similarly.  If  the  man  is  free  to  be 
a  criminal  or  not  to  be,  the  only  value  of  punishment 
is  to  get  even,  to  measure  the  crime  and  make  him 
suffer  as  he  has  made  others  suffer,  '  an  eye  for  an  eye.' 
On  the  other  theory,  punishment  is  merely  a  means  of 
reform.  It  gives  the  criminal  a  motive  for  refraining 
from  crime,  it  may  give  him  a  chance  to  form  new  habits, 
or  even  to  learn  some  new  trade  or  obtain  some  other 
means  of  support  that  shall  make  crime  unnecessary. 
In  the  worst  cases,  it  is  a  protection  to  society  by  remov- 
ing the  criminal  to  a  place  where  he  can  do  no  harm. 


THE    Q-ESERAL   PRINCIPLES    OF    ACTION  —  WILL       529 

In  any  case  the  idea  of  vengeance,  essential  to  the  older 
view,  plays  no  part.  When  it  is  considered  that  a  large 
percentage  of  criminals  are  mentally  deficient,  have  an 
intelligence  no  greater  than  a  child  of  ten,  the  modern 
theory  has  even  more  weight.  The  final  outcome  of 
the  two  theories  is  approximately  the  same,  but  the 
methods  of  inflicting  the  punishment  and  the  attitude 
while  carrying  it  out  are  altogether  dift'erent.  On  the 
whole  it  may  be  said  that  the  problem  of  the  freedom 
of  the  will  has  been  outgrown  rather  than  solved.  The 
present  attitude  toward  the  world  and  man's  place  in 
the  world  leaves  no  room  for  the  problem,  rather  than 
deciding  which  solution  is  the  correct  one. 

REFERENCES 

Ladd-Wood  WORTH :      Principles    of    Physiological    Psychology, 

pp.  542-565. 
AcH :  Ueber  die  Willenstatigkeit  und  das  Denken. 
Swift  :  Mind  in  the  Making. 
Bair  :  The  Acquirement  of  Voluntary  Control.    Psych.  Review, 

vol.  viii,  p.  474  £E. 


2M 


CHAPTER  XVI 

THE   SELF 

In  our  ordinary  life  and  in  much  of  scientific  psycho- 
logical discussion  frequent  use  is  made  of  the  term  self. 
For  popular  thought  the  most  important  part  of  con- 
sciousness and  of  the  world  as  a  whole  is  found  in  the  '  1/ 
To  it  practically  everything  is  referred.  It  is  regarded 
as  the  effective  agent  in  most  of  the  acts  of  the  individual, 
and  is  the  source  of  most  of  his  emotions.  A  notion 
that  has  so  large  a  share  in  our  mental  Hfe  must  be 
closely  examined  and  if  possible  explained.  We  must, 
as  psychologists,  take  the  same  attitude  toward  it  as 
toward  the  concrete  experiences  so  far  examined.  We 
must  seek  to  determine  how  far  it  is  open  to  examination 
as  a  mental  state,  what  effect  it  has  on  behavior,  and 
how  the  idea  must  have  developed  to  the  form  that  it 
takes  at  present.  It  is  for  us  one  phenomenon  among 
many,  in  spite  of  the  central  position  that  it  takes  in 
popular  discussion.  The  occasion  for  the  development 
of  the  self  comes  from  the  practical  needs  for  a  distinc- 
tion between  the  individual  and  others,  and  between  the 
individual  and  the  outside  world.  To  represent  these 
distinctions  concepts  have  gradually  grown  up  in  much 
the  same  way  that  concepts  of  external  things  develop, 
and  are  like  them  in  every  respect.     Each  has  some 

53° 


THE    SELF  531 

mental  content  and  means  a  large  number  of  distinctions 
and  processes  not  present  in  the  idea. 

The  Occasions  for  the  Self-concepts.  —  There  is  not 
one  concept  of  the  self  but  many,  corresponding  to  the 
different  occasions,  to  the  different  ways,  in  which  the 
outer  must  be  opposed  to  the  inner,  and  to  the  different 
Hnes  of  division  at  which  one  may  be  marked  off  from 
the  other.  Three  fairly  general  Hnes  of  demarcation 
may  be  drawn.  One  is  between  the  man  as  a  whole, 
including  the  body,  and  the  other  individuals  in  society. 
This  is  the  self  as  considered  in  law  and  in  most  of  the 
more  popular  objective  discussions.  A  second  Hne  of 
division  develops,  as  the  theoretical  interests  become 
dominant,  between  the  body  and  the  mental  states  or 
consciousness.  Finally,  a  third  notion  of  the  self  tends 
to  mark  oft  the  more  spontaneous  and  purposive  acts, 
those  that  are  foreseen  and  consented  to,  as  over  against 
the  acts  induced  by  external  forces  or  even  by  reflexes, 
—  the  acts  that  are  intended,  from  those  that  are  not 
intended.  The  first  we  may  call  the  physical  self,  the 
second  the  subjective  self,  the  third  the  effective  self. 
It  must  be  insisted  that  these  hnes  of  division  cannot  be 
sharply  drawn  and  that  they  are  not  consistent  from 
moment  to  moment.  At  any  particular  time  we  are 
interested  only  in  one  distinction  and  have  no  reference 
to  the  others.  While  there  are  many  gross  references 
and  many  occasions  on  which  it  is  desirable  to  unite 
the- three  concepts  into  a  single  one,  they  can  best  be 
discussed  separately  at  first,  and  then  united  so  far  as  is 
possible  in  a  common  notion.  In  considering  these 
concepts,  one  must,  as  in  all  cases,  distinguish  between 


532  FUNDAMENTALS    OF   PSYCHOLOGY 

the  conscious  element  used  in  representing  the  self, 
and  the  meaning,  —  the  thing  or  processes  represented 
by  that  concept. 

The  Physical  Self.  —  The  centre  of  reference  of  the 
physical  self  seems  to  be  the  body,  partly  as  it  is  seen  in 
the  field  of  vision,  partly  as  it  is  reconstructed  on  the  basis 
of  mirror  images  and  photographs  and  from  the  references 
of  friends.  The  meaning  of  this  physical  self  is  very 
much  wider.  It  is  used  to  refer  to  the  body,  together  with 
many  of  the  man's  immediate  possessions,  —  garments 
and  adornments  and  an  ever- widening  group  of  properties. 
The  physical  self  gradually  comes  to  be  indistinguishable 
from  the  physically  mine.  Houses  and  lands,  friends 
and  position,  all  of  the  things  that  one  must  struggle 
with  the  others  to  retain,  come  to  form  part  of  the  physi- 
cal '  me.'  This  physical  self  derives  much  of  its  meaning 
from  comparison  with  others.  One  tends  to  see  one's  self 
in  relation  to  others  about.  The  man's  picture  of  him- 
self and  of  his  possessions  always  involves  a  comparison 
with  others  and  with  the  ideals  that  these  set  for  his  own 
attainment.  The  wealth  of  the  individual  rich  and  poor 
alike  has  increased  enormously  in  the  last  century,  but 
nevertheless  the  line  is  quite  as  sharply  drawn  now  as 
ever  before,  since  the  relative  differences  are  approxi- 
mately the  same.  Similarly,  one's  opinion  of  one's 
physical  self  in  the  narrowest  sense  varies  with  the  in- 
dividuals with  whom  one  comes  in  contact.  One  feels 
one's  self  quite  a  man  among  small  men,  while  there  is 
a  decided  shrinking  when  with  men  of  large  stature. 
One  can  imagine  how  different  Gulliver's  impression  of 
himself  must  have  been  when  in  Lilliput  from  what  it 


THE    SELF  533 

was  among  the  Brobdignagians.  This  first  concept  rep- 
resents the  man  to  himself  as  a  man  among  men.  It  is 
the  self  in  the  most  practical  popular  sense. 

The  Subjective  Self.  —  The  second  concept  that 
represents  the  seh  as  opposed  to  the  body  is  of  much  less 
general  appHcation,  is  of  value  in  fact  only  in  connection 
with  more  theoretical  problems.  The  imaginal  centre 
of  the  concept  is  less  definite ;  probably  kinaesthetic  and 
organic  sensations  offer  what  Httle  there  is  of  actual 
content.  Sometimes  there  may  be  a  picture  of  the  seh 
as  the  spirit  of  the  savage,  or  the  ghost  of  the  ignorant, 
a  bodily  seK  with  the  physical  characteristics  subtracted, 
so  far  as  that  is  possible.  This  seems  relatively  rare 
among  psychologists,  and  others  have  not  reported  their 
results  in  sufficient  numbers  to  aft"ord  much  ground  for 
generalization.  Usually  one  is  satisfied  with  the  sensa- 
tions of  strain  in  the  head  or  in  the  chest  as  an  embodi- 
ment of  the  notion  of  the  self.  Its  appHcations,  too,  are 
relatively  few.  One  pictures  one's  self  as  rising  above 
bodily  Hmitations  in  ill  health ;  one  opposes  this  to  the 
sense  organs  and  their  imperfect  reports  of  the  world. 
In  psychology  it  is  made  to  include  consciousness  as 
opposed  to  the  acti\'ities  of  the  nervous  system  which 
are  purely  mechanical.  It  is  also  of  value  in  explaining 
dreams,  in  which  the  body  seems  to  be  in  one  place 
while  the  spirit  is  in  another.  When  we  attempt  to 
determine  to  what  place  sensations  are  ascribed,  there 
is  Httle  agreement  even  for  a  single  sense.  The  skin 
marks  the  boundary  of  the  self  for  touch ;  one  thinks  of 
one's  self  as  receixing  impressions  at  the  surface  and 
not  at  some  point   back   in    the    brain.     For   hearing 


534  FUNDAMENTALS    OF   PSYCHOLOGY 

and  sight  the  line  of  division  is  not  so  definite.  Most 
refer  the  sensations  to  the  object  in  the  outside  world, 
and  the  hearing  and  seeing  self  is  given  no  definite 
place.  Organic  sensations,  particularly  the  strain  sen- 
sations that  come  with  effort,  are  assigned  to  the  self  as 
opposed  to  the  body.  On  the  sensory  side,  then,  while 
every  one  would  assert  that  mind  and  body  are  to  be 
distinguished  and  that  the  '  I '  is  on  the  self  side,  the 
line  of  division  is  very  vague.  In  most  cases  one  would 
deny  any  of  the  seats  that  might  be  suggested  for  the 
processes  without  being  able  to  assign  a  better.  It  would 
not  even  be  matter  of  agreement  whether  the  self  in  this 
sense  included  all  of  consciousness,  or,  if  not,  exactly 
how  much  it  did  include.  Obviously,  this  second  concept 
corresponds  to  a  real  need  in  psychological  discussions, 
but  equally  obviously  the  concept  is  not  at  present  and 
probably  cannot  be  very  clear  cut,  either  in  its  image 
or  in  the  limits  that  it  makes  between  self  and  not-self. 
The  Active  Self.  —  The  third  concept  of  the  effective 
or  dynamic  self  represents  a  more  real  need  both  in 
psychology  and  in  practical  life.  In  nearly  every  one 
of  the  processes  we  have  considered,  there  has  been 
something  left  unsettled  in  the  explanation.  The 
final  presupposition  upon  which  explanation  of  each  was 
based  had  many  similar  elements  in  each  of  the  processes 
discussed,  and  different  theories  sought  an  explanation 
of  each  of  the  more  important  processes  in  some  other. 
In  attention,  first,  it  was  seen  that  there  was  a  final 
factor  which  was  characterized  by  the  feeling  of  effort 
reduced  in  part  to  sensations  of  strain,  the  condition 
of  which  was  found  in  social  pressure.     The  resulting 


THE    SELF  535 

attention  was  classed  as  voluntary.  The  same  factors 
were  at  work  in  the  control  of  associations  and  were  later 
seen  to  be  factors  which,  when  present,  increased  the 
rate  at  which  associations  were  formed.  In  the  emotions 
it  was  found  necessary  to  assume  some  tendency  toward 
an  end,  some  purpose  that  must  be  aided  or  hindered 
before  emotions  could  appear.  Finally,  in  action  it  is 
necessary  and  usual  to  distinguish  between  movements 
that  come  under  the  head  of  reflex,  instinct,  or  habit 
from  those  that  seem  to  depend  upon  wider  knowledge 
and  more  fully  conscious  purpose.  In  each  of  these 
there  is  something  in  common.  Voluntary  attention 
was  explained  by  the  social  instinct;  emotion  seemed 
dependent  upon  purposive  acti\dty  of  some  sort ;  action 
is  commonly  explained  by  attention  to  an  idea  or  an 
end.  Nor  is  the  interrelation  Kmited  by  these  state- 
ments. Many  authorities  would  explain  movement 
in  terms  of  feeling ;  others,  feeling  in  terms  of  move- 
ment ;  still  others,  attention  in  terms  of  movement ; 
others  again  attention  in  terms  of  feeling,  just  as  feeling 
and  movement  are  explained  by  some  in  terms  of  atten- 
tion. The  common  elements  in  all  of  these  processes 
and  the  last  term  in  the  explanation  of  each  are  often 
called  the  '  seK.' 

The  self  in  this  sense  has  practically  no  new  mental 
processes  to  represent  it.  One  may  think  of  it  as  the 
physical  self  or  a  ghostly  self.  The  only  sensational 
element  that  is  at  all  a  general  concomitant  is  the  mass 
of  strain  sensations  so  frequently  mentioned  as  constitut- 
ing the  feeling  of  effort.  These  are  taken  to  serve  as  an 
indication  of  activity  rather  than  as  a  direct  revelation 


536  FUNDAMENTALS    OF   PSYCHOLOGY 

of  the  self.  In  the  attempt  to  analyze  the  factors  which 
determine  the  course  of  this  activity,  we  again  have 
little  to  say.  Our  first  reduction  to  social  pressure 
proves,  when  seen  in  the  light  of  our  knowledge  of  in- 
stinct, to  reduce  largely  to  a  social  instinct  guided  by 
knowledge  obtained  from  the  society  in  which  the  man 
has  lived.  The  original  instinct  we  found  in  discussing 
emotions  developed  into  a  system  of  ideals,  and  these, 
as  they  became  more  active,  constituted  the  purposes  of 
the  individual.  The  study  of  action  offered  no  new 
contributions  to  our  explanation ;  action  was  an  outcome 
of  ideals  and  purposes  acting  in  selection.  There  was 
found  no  new  impelling  force,  nor  even  any  new  quality  or 
mental  state.  Study  of  the  self  adds  nothing  new.  As 
one  studies  his  own  self,  he  is  aware  of  the  fact  that  he  is 
acting  or  deciding,  but  he  gets  almost  no  light  as  to  what 
the  process  consists  in.  If  he  studies  another,  he  can 
trace  certain  factors  that  seem  to  play  a  part  in  making 
that  individual  decide  as  he  does,  but  neither  observa- 
tion of  one's  self  nor  of  another  can  show  directly  what  the 
determining  activity  is.  Curiously  enough,  tracing  the 
conditions  tends  to  discover  the  basis  of  the  activities 
that  are  believed  to  be  peculiarly  characteristic  of  the 
self  in  society.  The  more  intimately  personal  the  act, 
the  more  objective  are  its  conditions,  the  more  external 
the  forces  that  bring  it  about. 

In  each  of  these  more  active  processes,  one  feels  that 
there  is  something  that  must  be  explained  in  terms  of 
factors  that  cannot  be  definitely  formulated.  The 
tendency  is  always  to  bring  in  some  other  simple  process 
as  the  basis  of  the  explanation,  hence  the  reference  from 


THE    SELF 


537 


one  process  to  another  among  mental  states.  But, 
when  one  sees  that  one  can  complete  the  circle  and  come 
no  nearer  the  explanation  in  one  group  than  in  any  other, 
it  is  ob\ious  that  going  around  the  circle  has  not  furthered 
the  explanation.  Two  alternatives  remain  open.  One 
may  assume  either  some  highest  process  as  an  explana- 
tion of  all  the  others,  or  that  there  are  common  ele- 
ments in  each,  and  seek  to  determine  what  they  are.  The 
popular  mind  takes  the  first  of  the  alternatives,  —  as- 
sumes the  self  as  a  prime  determinant  and  makes  that 
the  final  force  in  all  spontaneous  actioij*  Since,  however, 
this  is  in  reality  no  explanation  but  merely  a  tagging 
of  the  facts  that  are  to  be  explained,  it  is  more  important 
to  determine  the  elements  common  to  each.  This  we 
may  find  in  the  developed  ideals  and  purposes,  which  in 
turn  are  to  be  referred,  first  to  instincts,  then  to  the  ideals 
of  society  taken  over  by  the  individual  largely  by  virtue  of 
the  social  instinct  —  the  instinct  to  seek  approval  —  and 
then  tested  and  confirmed  by  his  own  individual  experi- 
ence. If  other  factors  play  a  part,  they  cannot  be  traced, 
either  in  the  introspection  of  the  agent,  or  by  a  study  of 
the  behavior  of  others.  In  the  complexity  of  the  con- 
ditions that  act  upon  the  individual  we  are  not,  however, 
in  a  position  to  assert  that  no  others  are  effective  at  any 
point. 

The  Social  Factors  in  the  Self  Concept.  —  These  three 
concepts  of  the  self  tend  to  fuse  into  a  single  one  in  which 
something  of  each  is  retained,  and  are  more  or  less 
harmonized  into  a  unitary  whole.  The  representative 
self  has  something  of  the  body,  something  of  the  mental 
as  opposed  to  the  bodily,  more  of  the  strain  processes 


538  FUNDAMENTALS    OF   PSYCHOLOGY 

that  mark  it  as  active.  The  concept  is  ordinarily  em- 
ployed to  distinguish  between  the  self  and  society, 
between  the  '  I '  and  the  '  You,'  or,  objectively,  between 
the  characteristics  of  the  different  individuals  with  whom 
one  comes  in  contact,  who  must  be  used  in  the  accom- 
plishment of  one's  ends,  or  who  use  you  in  the  attain- 
ment of  theirs.  With  this  there  is  a  marked  effect  of 
the  life  in  society.  Both  the  static  and  the  dynamic 
features  of  the  self  are  appreciated  only  in  terms  of 
others  about.  One  has  an  idea  of  one's  own  peculiari- 
ties only  in  comparison  with  others.  One's  notion  of 
one's  self  as  a  whole  is  largely  an  image  of  the  self  as  it  is 
reflected  in  the  consciousness  of  others.  When  a  man  is 
among  men  of  smaller  attainments,  or  smaller  possessions, 
he  expands ;  when  he  is  with  men  of  larger  accomplish- 
ments or  reputation  or  possessions,  he  shrinks  just  as 
evidently.  Much  of  this  idea  of  the  self  depends, 
not  upon  actual  ability  and  possession,  but  upon  the 
imagined  attitude  of  others.  A  man  becomes  accus- 
tomed to  act  as  if  he  were  of  more  than  ordinary  im- 
portance, society  takes  him  at  face  value,  and  he  may 
go  for  years  or  even  through  life  without  having  the 
notion  corrected  either  for  himself  or  for  others.  On 
the  other  hand,  a  few  rebuffs  to  a  sensitive  individual 
will  repress  his  self  in  his  own  eyes  and  prevent  any  self- 
assertion.  If  he  has  high  ability,  it  may  go  for  years 
without  being  discovered.  Society  makes  its  judgment 
of  a  man  in  part  from  his  own  actions,  and  these  in  turn 
depend  in  some  measure  upon  the  estimate  he  thinks 
society  puts  upon  him.  The  process  is  a  circular  one. 
The  individual's  estimate  of  himself  is  what  he  beHeves 


THE    SELF  539 

to  be  society's  estimate  of  him.  On  the  other  hand, 
society's  estimate  of  the  man  is  very  largely  colored  by 
his  estimate  of  himself  and  his  consequent  bearing. 
The  way  in  which  the  indi\^dual  pictures  himself  and  the 
estimate  of  his  personal  capacity  are  largely  derived 
from  the  attitude  of  society  toward  him,  just  as  many  of 
the  forces  that  control  his  active  life  are  merely  an  ex- 
pression of  the  society  in  which  he  lives. 

The  Emotions  of  Self.  —  The  acti\'ities  and  processes 
that  develop  the  notion  of  self  are  found  very  largely  in 
the  emotional  group.  Wliat  we  called  the  more  com- 
plicated emotions,  those  which  come  from  the  interaction 
of  the  purposes  of  the  indi\'idual  with  the  en\'ironment, 
are  largely  social  in  character.  The  opposition  is  largely 
from  other  men,  and  the  emotion  is  usually  ascribed  to 
an  expanding  or  shrinking  of  the  self.  In  fact,  in  much 
of  our  dailv  life  the  onlv  reason  for  making  use  of  the 
notion  of  the  self  is  to  picture  the  origin  and  the  im- 
mediate source  of  the  emotion.  We  are  concerned  \\'ith 
the  self  only  in  moments  of  struggle  and  the  consequent 
success  or  defeat.  In  periods  of  quiet  contemplation  of 
external  objects  or  even  in  the  unhindered  manipulation 
of  things,  we  are  little  aware  of  the  self.  With  opposi- 
tion, particularly  from  other  men,  the  complex  of  emo- 
tions comes  into  play.  We  have  the  self-assertion  of 
effort,  the  elation  of  victory,  the  self-depreciation  of 
defeat.  That  these  emotions  are  always  of  a  social 
character  is  seen  in  the  fact  that  when  one  performs 
a  difficult  feat  when  alone,  there  is  always  a  thought  of 
what  some  one  else  might  think,  and  the  pleasure  in  the 
success  comes  largely  from  the  background  of  realization 


540  FUNDAMENTALS    OF   PSYCHOLOGY 

that  it  is  better  than  could  have  been  done  by  the  rival. 
The  onlooker  is  always  present  in  thought  if  not  in  reality, 
and  the  resultant  emotion  is  determined  by  the  way 
the  action  would  be  viewed  by  him  rather  than  by 
any  absolute  standard. 

These  self-regarding  emotions  constitute  the  core  of 
the  idea  of  the  self.  The  character  of  these  emotions 
seems  to  depend  upon  the  relation  between  the  ambitions 
of  the  individual  and  his  actual  accomplishments. 
James  puts  it  in  the  statement  that  self-esteem  equals 
success  divided  by  pretensions.  When  pretensions  are 
large,  success  small,  self-esteem  is  slight;  as  success 
grows  or  ambitions  diminish,  self-esteem  or  self-com- 
placency is  increased.  Self-esteem,  too,  is  only  affected 
when  success  or  failure  comes  in  some  field  in  which 
the  ambition  of  the  individual  lies.  A  scholar  may  very 
well  content  himself  with  little  of  the  worldly  goods, 
may  even  regard  wealth  as  somewhat  \ailgar,  since  he 
has  never  set  himself  towards  its  attainment.  The 
wealthy  man  of  affairs  returns  the  compliment  by  saying 
he  can  buy  the  services  of  a  scientist  much  more  cheaply 
than  he  can  the  advice  of  a  financial  expert,  —  that  learn- 
ing is  a  drug  in  the  market.  Each  is  satisfied  with  his 
own  position,  with  his  own  self,  as  he  has  never  attempted 
to  extend  the  self  in  the  field  of  the  other.  But  when 
men  of  affairs  come  into  rivalry  in  the  same  field,  the 
self  of  the  one  is  humiliated  as  the  other  attains  what  he 
has  himself  sought. 

These  emotions,  or  the  conditions  that  lie  behind  them, 
not  merely  determine  how  the  individual  shall  regard 
himself,  but  also  play  a  very  large  part  in  deciding  the 


THE    SELF 


541 


degree  of  effectiveness  of  the  indi\idual.  The  way  in 
which  the  self  is  regarded  determines  the  attitude  toward 
the  problems  of  life,  and  this  in  turn  is  an  important 
factor  in  the  success  or  failure  of  the  individual.  The 
character  of  the  indi\ddual,  \'iewed  either  from  within  or 
from  without,  is  closely  related  to  his  self-esteem. 

The  man  who  has  succeeded  and  lacks  a  sense  of  pro- 
portion or  the  sa\'ing  sense  of  humor  becomes  self-con- 
ceited. He  can  no  longer  remove  his  mental  gaze  from 
contemplation  of  his  own  capacities  and  of  past  successes, 
nor  can  avoid  expressing  this  appreciation  of  himself 
nor  conceal  his  expectation  that  others  will  express  their 
appreciation  of  that  position.  A  child  who  is  always 
the  centre  of  the  approving  household  develops  an  ex- 
aggerated notion  of  his  own  importance,  and  his  early 
success  in  business  or  scholarship  not  infrequently  sets 
an  attitude  of  self-satisfaction  that  cannot  be  disturbed 
even  by  later  failures  and  rebuffs. 

More  striking  is  the  expectation  of  failure  and  conse- 
quent lowering  of  ambitions  that  comes  with  crushing 
defeat.  A  man  of  middle  age  who  suddenly  finds  his 
system  of  ambitions  thwarted  and  all  of  the  accumula- 
tions of  pre\'ious  successes  swept  away,  seems  to  lose 
not  merely  all  of  his  ambitions,  all  of  his  self-respect, 
but  also  the  capacity  for  forming  new  purposes.  The 
self  disappears  or  is  profoundly  altered  wdth  the  despair 
that  follows.  Numerous  members  of  the  drifting  colonies 
of  ne'er-do-wells  of  our  large  cities  have  been  brought 
to  their  position  by  some  such  catastrophe.  The  man 
of  means  who  has  been  confident,  self-assertive,  and  per- 
sistent loses  his  wealth  through  some  mischance,  fails  in 


542  FUNDAMENTALS    OF   PSYCHOLOGY 

the  first  few  efforts  to  reestablish  himself,  and  then  mis- 
trusts himself  and  all  his  ventures,  — becomes  vacillating. 
Others  lose  confidence  in  him,  and  he  either  decides  that 
nothing  is  worth  while,  takes  a  care-free  attitude  toward 
the  world  and  attempts  nothing,  or  falls  into  despair 
and,  while  his  ambitions  are  retained,  he  gives  over  hope 
of  realizing  them.  In  brief,  the  system  of  ends  feeds  on 
success  and  grows  as  each  ambition  is  realized,  but  shrinks 
and  finally  disappears  with  repeated  failure.  Happy 
is  the  man  whose  ambitions  are  not  too  different  from 
his  capacities  and  to  whom  environment  is  sufficiently 
favorable  to  permit  the  realization  of  ambitions  in  suffi- 
cient degree  to  give  constant  encouragement,  without 
too  great  expansion  of  the  notion  of  his  capacity  and 
importance. 

The  self  is  in  this  sense  an  outcome  of  the  emotions 
which  originate  when  the  system  of  aims  receives  a 
shock  or  attains  one  of  the  subordinate  steps  toward 
an  end  or  the  end  itself,  and  the  emotions  are  in  many 
cases  referred  to  the  self  as  the  cause.  At  bottom,  the 
two  processes  are  probably  one.  The  self  is  a  concept 
that  serves  to  explain  both  the  emotions  that  originate 
from  the  progress  toward  ends  and  also  the  purposes 
themselves.  Here  again  we  seem  to  be  going  around  in 
a  circle.  Where  we  seek  the  self,  we  find  only  expres- 
sions, only  processes  that  have  needed  a  self  to  explain 
them,  rather  than  a  real  self.  On  the  other  hand,  when  we 
seek  the  explanation  of  certain  of  the  more  fundamental 
emotions,  we  are  said  to  discover  evidence  of  the  self,  or 
at  least  a  reference  to  the  self.  In  other  words,  wherever 
we  seek  the  self,  we  find  something  else,  but  whenever  we 


THE   SELF  543 

are  seeking  an  explanation  of  spontaneous  or  purposive 
action,  we  find  that  we  need,  or  at  least  wish  we  might 
have,  a  self. 

To  bring  together  the  results  of  our  investigation, 
the  self  is  a  group  of  concepts  originally  developed  to  rep- 
resent the  different  lines  of  division  between  the  man  and 
others,  between  the  mental  and  physical  processes,  and 
between  the  more  mechanical  and  the  more  spontaneous 
forms  of  action.  The  different  concepts  are  frequently 
fused,  at  least  in  part,  into  a  single  concept  which  be- 
comes representative  of  the  system  of  purposes  as  they 
control  actions,  which  gives  rise  to  emotions  and  serves 
to  designate  the  directing  forces  in  the  more  complicated 
mental  processes.  This  concept  is  the  point  of  reference 
for  all  our  self-regarding  ambitions,  it  is  the  self  we  are 
depressed  about  and  the  self  that  we  exult  over.  Never- 
theless it  must  not  be  assumed  that  something  corre- 
sponding to  this  self  need  be  found  by  introspection. 
Just  as  space,  regarded  as  a  concept,  was  needed  to  ex- 
plain certain  of  the  ways  in  which  we  saw  objects  and  the 
possibilities  of  movement,  so  the  concept  of  the  self  is 
merely  a  way  we  have  of  representing  to  ourselves  the 
immediate  facts  found  in  the  emotional  and  the  active 
life,  in  the  life  of  decision.  Examination  gives  us  nothing 
more  than  does  contemplation.  We  can  analyze  the 
way  in  which  we  perceive  space  relations  into  certain 
elements,  we  can  show  why  we  need  the  concept  of  space, 
but  we  do  not  expect  to  find  anything  more  by  any 
means.  Similarly  with  the  self,  we  can  point  to  certain 
strains  as  usually  present  when  we  think  'I,'  we  can 
show  why  it  is  needed  as  a  means  of  making  certain 


544  FUNDAMENTALS   OF  PSYCHOLOGY 

distinctions,  but  we  should  not  expect  to  find  anything 
more  by  observation  or  experiment,  —  and  we  do  not. 

Self -identity.  —  Extensions  of  this  empirically  derived 
self-concept  or  other  related  concepts  have  been  de- 
veloped to  solve  certain  of  the  more  theoretical  problems 
of  psychology  and  metaphysics.  One  of  the  simplest 
of  these  is  to  answer  the  question  of  how  the  continuous, 
ever-changing  series  of  mental  processes  should  all  be 
referred  to  the  same  self,  are  held  together  in  a  continu- 
ous stream,  and  are  regarded  as  states  of  the  perceiving 
self.  As  a  matter  of  fact,  the  practical  man  is  never 
bothered  by  this  problem.  In  observation  he  is  con- 
cerned only  with  the  things  that  are  meant.  It  is  only 
in  recognition  that  the  fact  that  he  has  seen  a  thing 
before  plays  an  important  part,  and  even  then  he  is 
more  interested  in  knowing  that  the  object  was  in  a 
certain  place  at  a  certain  time  than  with  the  fact  that  he 
saw  it  there.  The  different  experiences  are  held  to- 
gether as  parts  of  a  single  whole  by  the  interrelations 
that  make  recognition  possible,  that  make  it  possible  to 
refer  each  experience  to  a  definite  position  in  the  series. 
This  fact  of  reference  is  immediately  observed.  When 
the  self-concept  has  developed,  the  theorist  makes  that 
the  point  of  reference,  in  spite  of  the  difficulty  in  seeing 
how  an  actual  substantial  something  apart  from  the 
experiences  could  hold  them  together.  If  by  the  self 
we  mean  the  experiences  themselves  as  interrelated  one 
to  the  other,  the  notion  offers  less  difficulty. 

The  Unity  of  Consciousness.  —  Similar  theories  have 
suggested  that  the  fact  that  all  of  the  mental  states 
form  a  unity  at  any  moment  can  be  explained  in  terms  of 


THE   SELF  545 

the  self-concept.  Again  it  must  be  insisted  that  what  is 
or  can  be  noticed  is  the  unity,  so  far  as  that  exists, 
rather  than  an  '  ego.'  A  self  in  addition  to  the  states 
would  not  give  them  unity.  Rather  must  the  unity 
come  from  the  interconnection  of  mental  states,  the  sub- 
ordination of  all  to  some  single  one  that  is  the  central 
point  of  attention.  As  has  been  seen  frequently,  many 
processes,  some  corresponding  only  to  partially  aroused 
association  paths,  cooperate  in  constituting  any  single 
experience.  In  part  this  unity  is  explained  by  the 
nervous  system  in  which  many  neurones  are  always 
aroused  together  and  the  action  of  each  produces  a 
spread  of  impulses  to  all  of  the  others ;  in  part  it  is 
to  be  referred  to  the  interrelation  of  what  might  be 
regarded  as  single  elements  in  the  formation  of  concepts 
and  meanings,  the  real  mental  units.  In  any  case  the 
unity  is  within  the  mental  states,  not  a  unity  that 
comes  from  without  through  a  cormection  with  some- 
single  thing.  In  both  of  these  cases,  as  in  the  more 
empirical  active  and  emotional  processes,  the  facts  are 
to  be  found  in  the  continuity  and  unity  of  mental  pro- 
cesses ;  the  self-concept  is  developed  or  introduced 
to  explain  them.  It  is  merely  a  method  of  picturing, 
not  an  actual  experience.  Here  the  concept  is  even 
less  satisfactory  as  an  explanation  than  it  was  in  the 
preceding  instances. 

In  one  respect  the  more  cognitive  processes  which 
are  explained  by  this  more  passive  t}'pe  of  self  may  be 
combined  with  the  more  active  discussed  above.  The 
system  of  purposes  which  was  seen  to  be  the  deciding 
factor  in  dehberate  action  and  to  determine  the  character 


546  FUNDAMENTALS    OF   PSYCHOLOGY 

of  the  emotions  is  closely  bound  up  with  the  system  of 
knowledge.  Given  the  instinctive  basis,  each  experience 
modifies  that  instinct  and  gives  it  definite  content  at 
the  same  time  that  it  aids  in  the  construction  of  our 
system  of  concept  and  prepares  the  way  for  recognition 
and  for  meaning.  In  this  way  the  two  groups  of  systems 
become  closely  interwoven  and  are  for  the  most  part 
probably  merely  different  expressions  of  the  same  funda- 
mental unity.  When  active  in  the  control  of  perception 
and  reason,  we  term  the  result  the  cognitive  processes ; 
when  acts  and  emotions  are  involved,  we  speak  of  pur- 
poses. All  education  influences  each,  if  in  different 
degrees.  The  system  of  purposes  closely  determines 
the  acquisition  of  knowledge  and  the  use  made  of  it  in 
memory  and  reasoning,  while  the  knowledge  obtained 
has  its  effects  on  the  formation  of  purposes.  It  is  the 
close  interrelation  and  dynamic  interaction  of  all  parts 
of  experience  that  really  give  a  unitary  character  to  the 
acts  of  the  individual,  determine  his  intellectual  in- 
terests, and  make  possible  the  continuity  of  recognition 
and  of  meaning. 

Dissociations  of  Personality.  —  That  this  interrelation 
of  all  parts  probably  has  a  physical  basis  is  evident  from 
the  fact  that  in  certain  abnormal  individuals  each  of 
these  processes  may  be  broken  up  into  two  or  several 
systems,  each  of  which  acts  alone  to  produce  all  the 
capacities  of  a  whole  individual,  but  which  differ  in 
the  characteristics  of  each  of  the  partial  personaHties. 
The  cases  of  alternating  or  dissociated  personality  offer 
much  of  dramatic  interest,  which  cannot  be  treated 
here.    A  person  who  may  be  in  fair  health  will  suddenly 


THE    SELF  547 

find  himself  in  a  strange  situation,  with  no  memory  of 
anything  that  has  happened  before.  In  one  case  even 
the  most  rudimentary  knowledge  of  simple  things  was 
lost,  and  some  days  were  required  for  the  patient  to 
recognize  simple  objects,  and  still  longer  to  learn  to 
speak.  For  a  long  time  this  second  set  of  experiences 
remained  cut  off  from  the  old,  then  finally  the  patient 
awoke  again  with  no  memory  for  recent  events,  as  if  he 
had  just  waked  up  into  the  first  set  of  experiences. 
In  most  cases  the  second  self  comes  into  being  with  a 
portion  of  the  original  memories  and  experiences  of  the 
old.  There  is  a  dissociation  of  the  old  into  two  or  more 
parts,  rather  than  a  development  of  an  entirely  new 
series.  The  patient  suddenly  wakes  in  an  unfamihar 
environment,  with  no  memories  of  where  he  may  be  or 
of  recent  events,  but  with  full  command  of  language  and 
the  abihty  to  interpret  the  objects  about.  After  that 
the  different  personahties  or  groups  of  experiences  will 
alternate.  The  time  occupied  by  one  self  varies  greatly, 
as  does  the  occasion  for  the  change  from  one  to  another. 
Characteristics  of  the  Paxtial  Selves.  —  If  we  relate 
the  characteristics  in  which  the  selves  vary  and  the  marks 
that  distinguish  them  one  from  the  other,  to  the  facts 
that  have  led  to  the  development  of  the  self-concepts, 
we  find  that  practically  all  of  them  may  be  closely 
paralleled.  One  element  in  the  consciousness  of  self 
is  the  persistence  of  various  organic  sensations.  One 
feels  at  home  in  the  body,  if  we  may  indulge  in  meta- 
phor, because  the  strain  sensations  are  constant  from  one 
time  to  another.  Ribot  reports  some  cases  of  spHt  per- 
sonality in  which  the  organic  sensations  were  changed, 


548  FUNDAMENTALS    OF   PSYCHOLOGY 

and  suggests  that  the  change  might  in  part  have  ac- 
counted for  the  alteration.  Much  more  important  is 
the  break  in  the  Hne  of  association,  the  inabihty  to  recall 
an  event  in  one  state  which  has  occurred  in  another. 
The  train  of  memories  seems  to  be  broken  off  sharply 
when  the  personahty  alternates.  Everything  that  hap- 
pened in  one  state  can  be  recalled  in  that  state,  but 
all  the  experiences  of  the  other  state  are  lost.  There 
is  also  no  recognition  in  one  state  of  the  objects  seen  in 
another.  The  associations  that  connected  them  origi- 
nally are  completely  broken  while  the  associations  within 
each  group  persist.  It  is  this  characteristic  that  gives 
the  name  of  dissociated  personahty.  In  the  dissociation 
there  seem  to  be  pecuhar  divisions  of  the  original  self. 
In  the  Beauchamp  case,  reported  by  Dr.  Prince,  one  self 
kept  the  knowledge  of  French  of  the  original,  while  the 
others  were  entirely  without  it,  and  other  acquirements 
seemed  to  be  assigned  to  one  alone  of  the  personalities. 

Not  merely  are  the  acquirements  differently  divided, 
but  the  active  and  emotional  characteristics  seem  also 
to  vary.  One  self  will  be  highly  conventional  in  action 
and  desires,  will  respond  very  quickly  to  social  intincts, 
the  other  will  be  entirely  arbitrary  in  action.  The  differ- 
ence may  approach  that  so  vividly  pictured  by  Stevenson 
in  his  story  of  Dr.  Jekyll  and  Mr.  Hyde.  The  purposes 
of  the  two  selves  are  different  as  well  as  the  memories. 
This  is  in  accordance  with  our  explanation  of  the  de- 
velopment of  ideals  by  the  action  of  the  accumulated 
experiences.  When  the  systems  of  knowledge  divide, 
the  control  exerted  by  each  of  the  two  sets  of  ideals  or 
purposes  is  exerted  differently  according  to  the  com- 


THE    SELF  549 

ponents  that  make  it  up.  Dr.  Prince  suggests  that  in 
certain  cases  the  instincts  as  well  seem  to  be  di\ided. 
One  self  will  take  most  of  the  tender  and  benevolent 
instincts,  the  other  most  of  the  aggressive,  the  rebellious, 
antisocial  instincts.  WTiere  one  self  will  be  painfully 
conscientious  and  considerate  of  others,  the  second 
will  be  altogether  selhsh  and  indifferent  to  the  ordinary 
family  and  social  welfare.  With  the  break  in  knowledge, 
there  goes  a  corresponding  sudden  alternation  in  the 
effective  self.  The  indi^idual  shows  different  emotions, 
is  differently  controlled  in  action  and  in  thought.  Aside 
from  the  fact  that  both  selves  are  still  in  the  same  body, 
they  are  essentially  two  individuals,  Iwo  selves.  There 
is  no  memory  or  recognition  of  events  that  occur  to  the 
other  self,  there  is  no  consistency  of  action  betw^een  them, 
there  is  no  continuous  self-consciousness  from  one  to  the 
other.  Both  the  theoretical  and  practical  characteristics 
of  the  two  selves  are  altered. 

Dissociation.  —  If  we  attempt  an  explanation  from 
the  physical  side,  it  would  seem  that  the  various  eff'ects 
upon  the  nervous  system  are  retained  and  organized  into 
systems ;  that  these  systems,  while  ordinarily  acting  as 
units,  may  by  certain  shocks  be  dissociated  along  some- 
what definite  lines  of  cleavage  that  also  develop  as  a 
result  of  the  formation  of  distinct  systems.  WTien  the 
break  comes,  we  have  each  system  or  group  of  systems 
persisting,  but  with  no  bonds  of  connections  between 
them.  Each  system  continues  to  act  alone  and  to  con- 
trol the  responses  through  the  persistent  nervous  con- 
nections, guided  by  the  wider  series  of  partially  active 
neurones.     In  most  cases  certain  of  the  more  frequent 


550  FUNDAMENTALS    OF    PSYCHOLOGY 

nervous  activities  are  common  to  the  two  systems,  but 
this  shows  itself  only  in  the  persistence  of  the  nervous 
correlates  of  more  general  concepts  and  ideas,  to  which 
each  of  the  new  experiences  may  be  referred  and  be  under- 
stood, with  none  of  the  more  specific  references  that  con- 
stitute recognition.  The  normal  self  has  as  its  correlate 
on  the  physical  side  a  complete  system  or  system  of 
systems,  from  all  of  the  more  important  parts  of  which 
impulses  might  pass  to  awaken  all  of  the  other  parts,  — 
a  system  that  embraces  and  unifies  many  lesser  systems, 
all  of  which  are  connected.  So  long  as  this  system  re- 
mains unbroken,  memory  is  continuous,  memories  from 
all  parts  of  the  life  may  be  recognized  and  the  actions 
are  sufficiently  controlled  to  be  consistent.  That  this 
is  the  basis  for  the  characteristics  that  we  have  regarded 
as  constituting  the  peculiar  condition  of  the  self  is  evident 
from  the  fact  that,  when  this  complete  system  is  broken 
into  two  or  more  groups  of  systems,  two  or  more  selves 
make  their  appearance. 

Hypnotism  and  Other  Forms  of  Dissociation.  —  Not 
only  does  dissociation  arise  spontaneously,  but  in  many 
individuals  it  may  be  induced  at  will.  If,  for  example, 
a  patient  be  asked  to  keep  attention  continuously  fixed 
upon  some  one  object,  he  will  pass  into  a  cataleptic 
stage,  his  muscles  will  stiffen,  and  he  will  gradually  to  all 
appearances  become  unconscious,  and  in  the  higher 
degrees  of  the  resulting  abnormal  condition  will  show 
many  of  the  phases  of  the  dissociated  personaHty.  The 
state  is  much  more  readily  induced  if  the  patient  re- 
mains passive  and  is  told  from  time  to  time  that  he  is 
losing  consciousness.    When  most  completely  hypnotized, 


THE    SELF  551 

the  patient  is  highly  suggestible,  will  do  anything  that 
he  is  told  to  do,  may  even  be  made  to  take  on  different 
personaHties.  On  waking  there  is  ordinarily  no  memory 
of  what  has  happened  during  the  h>pnotic  state,  although 
when  hypnotized  again,  the  p^son  may  recall  the  events 
of  this  period.  The  close  relation  between  this  and  the 
phenomena  of  the  dissociated  self  is  indicated  by  the 
fact  that  change  from  one  self  to  the  other  often  can  be 
induced  by  suggestion  in  the  hypnotized  state  and  that 
when  hypnotized  in  one  state, ,  that  seK  wdll  recall 
events  experienced  in  other  states.  In  many  diseased 
conditions  there  is  e\^dence  that  partial  dissociation  of 
these  systems  may  take  place  and  may  be  responsible 
for  the  disease.  Hysteria  is  largely,  if  not  altogether, 
due  to  a  breaking  away  from  the  whole  of  some  one  of 
the  systems.  This  may  not  be  large  enough  seriously 
to  disturb  the  higher  coordinations  of  the  self,  but  does 
prevent  the  larger  system  from  recei\'ing  impressions 
from  certain  sense  organs  connected  with  the  dissociated 
elements  and  may  also  cause  a  paralysis  of  the  muscles 
that  are  either  permanently  or  temporarily  united  with 
those  dissociated  elements. 

Consciousness  and  Subconsciousness.  —  Numerous 
theories  have  suggested  that  the  self  is  seldom  com- 
pletely united,  that  there  are  always  larger  or  smaller 
groups  of  experiences  or  memories  which  are  independent 
of  the  larger  system.  Thus,  Freud  at  present  explains 
dreams  and  many  of  the  accidents  of  daily  Kfe  as  well  as 
the  witty  sayings  of  the  normal  individual  by  the  fact  that 
he  has  an  organized  complex  of  elements,  which  usually 
contributes  Httle  to  consciousness  but  which  on  occasion 


552  FUNDAMENTALS    OF   PSYCHOLOGY 

will  be  excited  and  when  aroused  open  new  possibilities 
for  good  or  evil  in  the  individual.  This  detached  com- 
plex is  frequently  said  to  have  all  of  the  elements  of  the 
normal  or  total  self,  to  have  desires  of  its  own,  to  do 
thinking  for  itself,  —  in  fact,  to  constitute  a  true  self, 
which  is  also  regarded  as  being  conscious.  Many  facts 
point  to  the  presence  of  these  complexes,  and  the  asser- 
tion that  a  definite  consciousness  attaches  to  them  raises 
many  questions  as  to  what  our  ordinary  consciousness 
may  be,  upon  what  it  depends.  It  must  be  granted 
that  these  subconscious  systems  give  rise  to  many,  if 
not  all,  of  the  effects  of  the  complete  system.  We 
could  personify  them  as  readily  as  we  do  the  experience 
of  many  other  individuals.  The  only  test  of  conscious- 
ness from  the  inside,  however,  is  the  personal  test  —  that 
we  are  aware  of  it  in  introspection  —  and  by  definition 
this  '  subconscious '  does  not  belong  to  that  class.  So 
much  of  what  contributes  to  our  personal  consciousness 
in  very  many  important  respects  is  not  itself  directly 
conscious  that  the  difference  may  not  be  important.  Of 
all  of  the  myriad  activities  in  the  nervous  system,  only  a 
few  can  be  known  at  any  moment,  and,  as  has  become 
apparent  from  the  study  of  meaning  and  related  pro- 
cesses, no  one  of  these  is  consciousness  of  and  for  itself 
alone.  It  must  always  be  grouped  with  a  number  of 
other  activities,  if  consciousness  is  to  result.  Even  then 
consciousness  is  limited,  in  most  cases,  to  the  things  re- 
ferred to  or  meant,  rather  than  to  the  elements  that  are 
supposed  to  carry  the  meaning.  Each  group  of  nervous 
elements  may  by  its  activity  contribute  to  the  conscious- 
ness of  the  total,  but  the  conditions  of  consciousness 


THE   SELF  553 

must  still  be  regarded  as  obscure.  The  most  that  can 
be  said  is  that  of  the  different  systems  that  are  found 
wifhin  the  nervous  system  at  any  one  time,  the  largest 
and  most  active  is  accompanied  by  consciousness.  The 
others  are  either  completely  suppressed  as  in  the  case  of 
the  complexes  of  the  subconscious  or  unconscious,  or 
the  minor  systems  contribute  only  in  some  slight  degree 
to  the  total  consciousness.  Consciousness  seems  to  be 
determined  by  or  to  accompany  the  activity  of  a  system 
of  nervous  elements,  connected  by  \drtue  of  acting  to- 
gether in  various  systems  of  experiences*  How  many 
elements  may  be  included  in  what  corresponds  to  the 
centre  of  consciousness,  and  how  far  less  central  elements 
can  play  a  part,  no  one  can  say.  It  can  be  asserted  with 
assurance  that  even  the  most  central  features  of  con- 
sciousness correspond  to  the  action  of  many  neujones, 
show  the  effect  of  many  experiences,  and  represent  even 
more.  WTiere  the  limits  are  to  be  drawn  is  not  to  be 
confidently  stated. 

Very  Uttle  of  the  nervous  action  is  really  accompanied 
by  consciousness,  although  very  much  of  that  activity 
has  an  effect  upon  consciousness.  Much  the  same 
statement  may  be  made  of  the  functions  of  the  individ- 
ual as  we  deal  with  him  in  psychology  and  everyday 
life.  We  know  that  he  remembers  and  recognizes,  that 
he  perceives  objects  and  reaches  conclusions,  that  he 
feels  and  chooses ;  we  can  even  trace  many  of  the  con- 
ditions of  these  different  operations,  but  he  himself  is 
conscious  of  Httle  more  than  the  outcome,  —  the  causes 
are  not  revealed  in  consciousness.  There  is  no  occasion, 
then,  to  spend  much  time  on  the  question  whether  some 


554  FUNDAMENTALS    OF   PSYCHOLOGY 

of  the  hidden  complexes  of  neural  activities  are  accom- 
panied by  consciousness,  when  we  know  so  little  of  the 
causes  and  effects  of  the  highest,  most  fully  revealed 
consciousness.  A  close  analysis  of  seK-consciousness 
gives  as  little  reward.  One  has  certain  concepts  that 
are  represented  by  more  or  less  definite  imagery,  but 
again  the  important  factor  is  not  the  imagery  but  what 
the  imagery  represents.  This  is  our  notion  of  the  whole 
as  active,  of  the  processes  that  direct  our  thoughts  and 
acts,  a  continuous  experience  with  the  possibility  of 
referring  from  any  part  to  any  other.  All  these  are  in- 
volved in  the  self  idea,  but  are  not  all  conscious  at  any 
time.  The  consciousness  of  seK  is  seldom  present  and  is 
of  little  importance  when  present,  the  self  as  the  whole 
man  active,  as  the  unity  and  continuity  of  experience,  is 
fundamental.  It  must  be  emphasized  that  this  is  not 
a  single  experience  among  the  other  experiences,  it  is 
not  something  of  which  we  may  become  immediately 
conscious ;  on  the  contrary  it  is  the  man  with  all  of  his 
experiences  and  activities  viewed  as  a  whole. 


INDEX   OF   NAMES 


Ach,  N.,  520,  523. 
Alrutz,  S.,  175- 
Angell,  J.  R.,  303. 
Angell,  F.,  369. 
Aschaffenburg,  G.,  258. 

Bagley,  W.  C,  341- 
Bair,  J.  H.,  364.  505- 
Barany,  R.,  63. 
Barret,  B.,  523  ff. 
Batson,  508. 
Benussi,  V.,  335- 
Bezold,  von,  165. 
Biedermann,  213. 
Bills,  M.,  134- 
Bing,  R.,  97. 
Blix,  M.,  171. 
Book,  W.  F.,  505. 
Bourdon,  B.,  286. 
Breed,  F.  S.,  436. 
Breuer,  J.,  199- 
Broca,  69,  76,  80. 
Brown,  Cram,  199. 
Brown,  Thomas,  197. 
Bruner,  F.,  152. 
Br>-an,  W.  L.,  505. 

Calkins,  M.  \V.,  259  f- 
Camion,  \V.  B.,  203,  475  2- 
Carlson,  A.  J.,  203. 
Charcot,  233. 
Chevreul,  M.  E.,  185. 
CliSord,  W.  K.,  94- 
Coleridge,  S.  T.,  361. 
Colvin,  S.  S.,  386. 
Cope,  E.  D.,  398. 
Courtier,  J.,  458. 
Craig,  W.  C,  426. 
Cushing,  H.,  71. 

Dalton,  J.,  123. 

Darwin,  C,  402,  41S  2-.  483  f- 


Dawes-Hicks,  310. 
Descartes,  R.,  92,  467,  469. 
Dewey,  J.,  419,  486. 
Diamandi,  381. 
Dodge,  R.,  235. 
Donaldson,  H.  H.,  171. 
Dunlap,  K.,  97. 

Ebbinghaus,  H.,  214,  260,  346  ff.,  350, 

354,  357,  359  f-,  368,  376,  380. 
Edelmann,  152  f. 

Fab  re,  422. 

Fechner,  11,  210,  214,  220  f.,  251. 
Femald,  235. 
Ferree,  325. 
Flechsig,  70,  74. 
Flourens,  67. 
Franz,  S.  I.,  75. 
Freud,  S.,  551. 

Frey,  von,  175  f.,  178,  181,  186,  199. 
213,  277. 

Galen,  494  f. 

Gall,  67. 

Galton,  F.,  152,  233  f-,  257,  260. 

Goldscheider,  171  f.,  176,  178,  i97  f-, 

276. 
Greenwood,  144. 

Hardesty,  168  f. 

Harter,  505. 

Haycraft,  195. 

Hayden,  369. 

Hayward,  369. 

Head,  H.,  178,  182. 

Heller,  305. 

Helmholtz,    103,    121    f.,    128,    132   f-, 

137    f.,  140,   145,   156,   162,   164  flf., 

170. 
Hensen,  169. 

Hering,  89,  121  f.,  124,  132,  143,  218  f. 
Hermann,  157. 


555 


556 


INDEX    OF    NAMES 


Herrick,  97. 
Hobbes,  98. 
Hobhouse,  422. 
Hollingworth,  369. 
Howell,  144. 
Huber,  22. 
Hunter,  325. 

Inaudi,  381. 

James,  321,  335,  442,  472  £f.,  540. 

Jastrow,  408. 

Jennings,  18,  501. 

Jost,  354  f- 

Judd,  310,  319,  SOI. 

Kent,  224. 

Kiesow,  191. 

Koehler,  157  f. 

Konig,  156, 

Kreidl,  201. 

Kries,  von,  104,  132  £f.,  142  S. 

Kiilpe,  228,  388,  450,  489. 

Ladd-Franklin,  142,  144. 
Lange,  472. 
Langley,  213,  402. 
Lehmann,  368  f.,  373  f.,  458. 
Liepmann,  82. 
Lipps,  463. 
Locke,  98,  317. 
Lotze,  274  f. 
Luft,  153. 

MacDougall,  W.,  97,  425,  442,  482, 493. 

Mach,  199. 

Marshall,  H.  R.,  466. 

Martin,  L.  J.,  221,  230. 

Mayer,  160. 

Meumann,  E.,  349,  352  f.,  357  f.,  376, 

380  f.,  386. 
Meyer,  A.,  77. 
Meyer,  G.  C.,  372. 
Meyer,  Max,  153  f..  158,  169. 
Michotte,  523  ff. 
Mill,  197. 
Morgan,  442. 
Mulhall,  369. 
Muller,  G.  E.,  142,  214,  222,  347,  351  f., 

360,  364,  377. 


MUller,  H.,  114. 

Muller,  J.,  287. 

Myers,  C.  S.,  144,  236,  303  f.,  335. 

Nagel,  208. 

Oehrwall,  188. 
Ogden,  357. 

Parsons,  144. 
Pawlow,  459,  475. 
Perkins,  354. 
PUzecker,  222. 
Plato,  471. 
Preyer,  152  f. 
Prince,  548. 
Priim,  523. 
PuKrich,  286. 

Pyle,  353. 

Radossawljewitsch,  359. 
Revesz,  154,  158. 
Rivers,  182,  184. 
Rosanoflf,  224. 
Royce,  455*  f- 
Riickle,  377,  381,  384. 
Rutherford,  169. 

Schumann,  347,  364. 

Shambaugh,  168. 

Shand,  469,  481,  492. 

Shepard,  364,  436,  458. 

Sherrington,  84,  85,  89  f.,  475,  479. 

SoUier,  473. 

Spinoza,  469. 

Spurzheim,  68. 

Steffens,  352. 

Stern,  323. 

Stout,  463,  493. 

Stratton,  279. 

Streeter,  63,  201. 

Strieker,  234. 

Strong,  C.  A.,  97, 

Strong,  E.  K.,  369. 

Swift,  505. 

Thorndike,  499. 
Thunberg,  175. 

Titchener,  144,  197,  215,  241,  33s,  419, 
466,  498. 


INDEX    OF    NAMES 


557 


Ulrich,  355. 
Urbantschisch,  i6o. 

Vogelsonger,  364. 
Volkmann,  276. 

Wallace,  415  flf. 

Watson,  355,  42s,  442,  503. 

Weber,  E.  H.,  213,  276. 

Wernicke,  76. 

WTieatstone,  296. 

Wien,  213. 

Wirth,  241. 


Witasek,  321. 
Wohlgemuth,  327. 
Wolfe,  366  f.,  370,  373. 
Wolff,  10. 
Woodrow,  329. 
Woodworth,  97,  388. 
Wright,  402. 

Wundt,  214,  240,  279,  309,  453  Q.,  461, 
464,  494. 

Zander,  191. 
Zeitler,  337. 
Zwaardemaaker,  194  f.,  197. 


INDEX  OF   TOPICS 


Accommodation  in  perception  of  space. 
290. 

visual,  for  distance,  107  f. 
Achromatic  series,  127  f. 
Action,  origin   of,  and   consciousness, 
498  f. 
^^Adrenal  glands  in  emotion,  476  ff. 
Affection    as   attribute    of    sensation, 
4Sof. 

bodily    accompaniments     of,     457- 
460, 

and  feeling,  444  f. 

and  intensity  of  sensation,  455  ff. 

qualities  of,  452  f. 

and  sensation,  445-449. 
After-images  of  movement,  323  ff. 

negative,  125. 

positive,  136. 

colored,     as     effect     of     brightness 
stimuli,  136  f. 
After- sensations  of  tone,  166  f. 
Angle  illusions,  312  ff. 
Aphasia,  76  ff. 
Apraxia,  81  f. 
Association  areas,  74  f. 

laws  of,  223  ff. 

control  of,  257-262. 

controlled  by  conditions  of  attention, 
259  f- 

nervous  basis  of,  225  ff. 
Attention,  definition  of,  238  f. 

duration  of,  248  ff. 

forms  of,  262  ff. 

and  intensity  of  sensation,  239  f. 

motor  concomitants  of,  241  ff. 

neural  explanation  of,  265  f. 

objective  conditions  of,  250  f. 

physiological     accompaniments    of, 
245  f- 

range  of,  246  ff. 

subjective  conditions  of,  251  ff. 

waves,  249. 


Attributes  of  sensation,  101-102, 
Auditory  nerve,  connections  of,  56  ff. 
Auditory  perception  of  space,  302. 
Auditory  space  of  the  blind,  304  ff. 
Axones,  23  f. 

Basilar  membrane,  151. 

Beats,  160. 

Behavior,  4  ff. 

Belief,  409  ff. 

Binocular  vision,  283  f. 

Blind  spot,  114. 

Body  and  mind,  92-96. 

Brain  localization,  67-79. 

Brain  stem,  function  of,  49  f. 

Centrally  excited  sensations,  qualities 

of,  227-233. 
Cerebellum,  62  ff. 
Cerebrum,  lobes  of,  66. 
Cerebrum,  parts  of,  65  f. 
Change    as    condition    of    attention, 

251. 
Choice,  519  ff. 
Choroid  coat,  105. 
Ciliary  muscle,  108  f. 
Classification  of  psychologies,  10  ff. 

of  sensations,  99. 
Clearness,  degrees  of,  241. 
Cochlea,  151  f. 
Cognition,  375. 
Color  bhndness,  123  f. 
Colors,  complementary,  122. 
Color  mixture,  116  ff. 
Colors,  primary,  120  f. 
Color  pyramid,  116  ff. 
Color    theory,    Mrs.    Ladd-Franklin's, 
142  f. 

Helmholtz',  139  f. 

Hering's,  140  ff. 
Combination  tones,  i6i  f. 
Concept,  development  of,  396  f. 


558 


INDEX   OF   TOPICS 


559 


Concept,  in  knowledge,  397  ff. 

in  perception,  342  flf. 

as  representative;  394  f. 

as  type,  395  f. 
Conjunctiva,  104. 
Consciousness,  4  fif. 

and  cortical  action,  91  f. 

and  movement,  510  f. 
Contrast  and  confluxion  in  optical  illu- 
sions, 310  f. 
Contrast,  color,  126. 
Convergence  in  perception  of  depth, 

290  S. 
Cornea,  105  f. 
Corpora  quadrigemina,  51. 

functions  of,  64. 
Corresponding  points,  285  f. 
Corti,  organ  of,  162  f. 
Cutaneous  sensations,  170-185. 
Cutaneous  sense  organs,  181. 

Deduction,  412. 

Definition  of  psychology,  1-7. 

Dendrite,  23  f. 

Depth,  perception  of,  290-302. 

Deuteranope,  133  f.     '^ 

Difference    limen   for    visual    extent, 

281. 
Dioptrics  of  eye,  109  f. 
Dissociation  of  personality,  546  ff. 
Dissociation,  physiological  ^explanation 

of,  549  f. 
Double  Bnages  in  perception  of  depth, 

292  ff. 
Doubt,  410. 
Duplicity  theory  of  vision,  129. 

Ear,  structure  of,  145-152. 

Ectoderm,  29  f. 

Education  and  attention,  254  f. 

EinfUhlung,  463. 

Emotional  control,  490  f. 

expression,  origin  of,  481  ff. 
Emotions,  classification  of,  468,  487  f . 

James-Lange  theory  of,  472  ff. 

quality    of    and    bodily    expression, 
479  ff- 

physiological  processes  in,  417  f. 

action    of    sympathetic    system    in, 
475  ff. 


Empiricism  and  retinal  correspondence, 
288. 

in  space  perception,  319  ff. 
End  brush,  22. 
Entoderm,  29  f. 
Epicritic  sensibiUty,  184  ff. 
Equilibration,  sense  of,  202  f. 
Eustachian  tube,  150. 
Evaluation,  404  f. 
Eye  muscles,  281  ff. 
Eye,  reduced,  109  f. 

structure  of,  104-114. 

Facihtation,  88. 
Fechner's  paradox,  285. 
Feeling,  definition  of,  443. 

theories  of,  460-466. 
Fifth  nerve,  58,  61. 
FUcker,  visual,  136. 
Forgetting,  359  ff. 
Fovea,  113  f. 
Freedom  of  will,  525  ff. 
Frontal  lobes,  75  f. 

Genetic  psychology,  12. 
Geniculate  bodies,  51. 
Goal  idea  in  association,  258  f. 
Gray  matter,  28. 

Habit,  87,  218  f. 

Haze,  in  depth  perception,  299  f. 

Hearing,  theories  of,  162-170. 

telephone,  theories  of,  169  f. 

Shambaugh  theor>'  of,  168  f. 
Hemispheres,  development  of,  38  f. 
Heredity  and  attention,  256  f. 
Hering  figure,  312. 
Horopter,  288. 
Hunger,  203. 
Hypnotism,  550. 

Imagination,  385  f. 
Imitation,  437  f. 

learning  by,  509  f 
Induction,  413. 
Inference,  405  f. 

trial  and  error  in,  406  ff. 
Inhibition,  89  f. 

associative,  358  f. 

reproductive,  364  f. 


56o 


INDEX    OF   TOPICS 


Instinct,  classification  of,  425  f. 

definition  of,  420  S. 

individual,  426  ff. 

and  learning,  435  ff. 

origin  of,  439  ff. 

racial,  430  f. 

social,  431-435. 

variations  in,  422  f. 
Interactionism,  93  ff. 
Intraocular  pressure,  105. 
Introspection,  3. 
Iris,  106  f. 

Jost's  Law,  356,  360. 
Judgment,  402  ff. 
Judgments  of  relation,  404  f . 

Kinaesthetic  sensations,  197  ff. 

Learning,  active  repetitions  in,  357. 

distributed  repetitions  in,  354  ff. 

effect  of  length  of  series  upon,  348  f. 

effect  of  rate,  357. 

effect  of  repetitions  in,  347  f. 

grouping  in,  350. 

methods  of,  in  animals,  499  ff, 

by  whole  and  by  part,  352  ff. 
Life  processes,  16. 
Light,  white,  121  f. 
Limen  of  'two-ness,'  tactual,  276  ff. 

visual,  278  ff. 
Local  sign,  retinal,  278  ff. 

tactual,  274  f. 

Meaning,  explanation  of,  377  f. 

as  incentive  to  movement,  512  f. 

and  learning,  376. 

and  perception,  268  f. 

in  reasoning,  388  f. 

and  recognition,  373  ff,  391  ff. 

theories  of,  388  ff. 
Medulla,  50  f.,  60. 
Medullary  sheath,  25. 
Memory,  i  f.,  345-386.      •* 
Memory  after-image,  220,  247. 
Memory,  dependence  upon  age,  380  f. 

experimental  methods,  346  f. 

image,  220. 
Memory  image,  projection  of,  230  ff. 
Memory,     individual    differences    in, 
379  f. 


Memory,  systems,  383, 

training,  382,  384  f. 

types,  233  ff. 

imaginal  types  and  capacity  of,  381  f. 
Mesoderm,  29  f. 
Methods  of  investigation  in  psychology, 

2ff. 

Mood,  493. 

Motor  cortex,  71  f. 

Motor  inhibition  in  attention,  244  f. 

Movement,  control  of,  515  f. 

excited  by  sensation,  497  f. 

incentives  to,  511  ff. 

methods  of  learning  new,  499  ff. 

mimetic,  243  f. 

in  perception  of  depth,  300  f. 

visual  perception  of,  322-327. 
Miiller-Lyer  illusion,  308  ff. 

Nativism    in    retinal    correspondence, 

287  f. 
Nativism  in  space  perception,  318  ff. 
Nature  of  nerve  impulse,  39  ff. 
Nervous  system,  development  of,  32- 

38.. 
Neural  groove,  31  f. 
Neurilemma,  25. 
Neuroglia,  24,  26,  32. 
Neurones,  21  ff. 

functions  of,  28  f. 
Nissl  bodies,  22. 
Nodal  point,  1 10. 
Noise,  155  f. 
Nucleus,  21. 

Object,  nature  of,  268  f. 

perception  of,  269. 
Observation,  3. 
Odors,  mixtures  and  compensations  of, 

196. 
Olfactometer,  195. 
Olfactory  qualities,  193  ff. 
Olfactory  sensations,  192-197. 
Optic  nerve,  connections  of,  58  f. 
Optical  illusions,  307-315. 
Optogram,  115. 
Ossicles,  auditory,  146  ff. 

Pain  sensations,  176  ff. 
spots,  178,  181. 


INDEX    OF   TOPICS 


561 


Paradoxical  cold,  175. 

Pathological  psychology',  12  f. 

Perception  and  sensation,  267  f. 

Perseveration,  221  f.,  360  f. 

Perspective,  298  f. 

Pigment    cells,    displacement     of,    in 

bright  light,  115. 
Pigment  cells,  105. 
Plateaus  in  learning,  505. 
Play,  438  f. 

Poggendorf  illusion,  312. 
Proof,  411  ff. 
Protanope,  133  f. 
Protopathic  sensitixaty,  183. 
Protozoa,  17  S. 
Pseudoscope,  296. 
Psycho-physical  parallelism,  93  ff. 
Pupil,  106. 

Pupillarj-  reflex,  60,  62,  107. 
Purkinje  phenomenon,  129  flf. 
Purpose,  a  condition  of  attention,  253  f . 

in  emotion,  469  f. 
P>Tamidal  tracts,  47  ff,  55. 

Reading,  336  £f. 
Reasoning,  stages  of,  401  f. 
Recall,  362  ff. 

subjective  conditions  of,  261  f. 
Recognition,  366-379. 

association  theorj'  of,  370  f. 

forms  of,  367. 

immediate,  371  f. 

and  meaning,  373  ff.,  391  fif. 
Reflexes,  nature  of,  41  f. 
Relations  of  psychology  to  other  dis- 
ciplines, 8  ff. 
Remote  sensations  in  control  of  action, 

516  f. 
Resident  sensations  in  control  of  move- 
ment, 515  f- 
Retention,  nature  of,  217  ff. 
Retina,  structure,  110-114. 
Retinal  rivalrj',  285. 
Retinal  streaming,  325. 
Rhythm,  327-331- 

effects  of,  in  learning,  350  ff. 

theories  of,  329  ff. 
Rods  and  cones,  in  f. 
Rod  v-ision,  129  f. 
Rolando,  fissure  of,  67. 


Sclerotic  coat,  104  f. 
Selection,  attention  as,  240  f. 
Self,  active,  534  ff. 

as  concept,  530  f. 

emotions  of,  539  ff, 

identity,  544. 

physical,  532. 

subjective,  533  f, 

tmity  of,  544. 
Sensory  cortex,  72  f. 
Sensory-  nerves,  regeneration  of,  182  fl 
Sentiment,  492. 

Shadows  in  perception  of  depth,  301. 
Sheath  of  Schwann,  25. 
Skill,  acquisition  of,  504  ff. 
Smell,  sense  organs  of,  192. 
Social  factors  in  self  concept,  557. 
Social  pressure  in  attention,  253  ff. 
Sounds,  direction  of,  303. 
Sound  waves,  145. 
Space  perception,  273-321. 

"theories  of,  315-321. 
Spatial  senses,  273  f. 
Specific  energies,  doctrine  of,  205-209. 

in  taste,  188  ff. 
Speech  functions,  78  f. 
Spinal  cord,  reflexes  of,  42  ff. 

tracts  in,  45. 
Spinal  gangha,  34  f. 
Stapedius  muscle,  149. 
Static  sense,  199  ff. 
Stereoscop)e,  294  ff. 
Subconsciousness,  551. 
Supplementation  in  perception,  339  f. 
Suspensory-  ligament,  108. 
Sylvius,  fissure  of,  66. 
Synaesthesia,  236  f. 
Synapse,  85  ff. 

Tactual  space,  274-278. 
Taste  buds,  187. 

contrast,  190  f. 

fusion,  190  f. 

nerves  of,  189  f. 

sensations  of,  185-igi. 
Teleostereoscope,  297. 
Temperament,  494. 
Temperature  scale,  174. 
Temperature  spots,  171  f. 
Tensor  tympani,  149. 


562 


INDEX    OF   TOPICS 


Thalamus,  51. 

Thirst,  204. 

Tickling,  205. 

Tigroid  bodies,  22. 

Time,  perception  of,  331-335. 

theories  of,  333  ff. 
Tonal  fusion,  158,  270  ff. 
Tone  color,  154  f. 
Tone,  sensations  of,  152  ff. 
Touch  spots,  176. 
Trial  and  error  in  learning,  501  ff. 
Tympanum,  146. 

Vesicles,  brain,  35  ff- 
Vicarious  functioning  in  nervous  sys- 
tem, 83. 
Vision  of  born  blind,  3i6'ff. 
peripheral,  124  f. 


Vision,  qualities  of,  116  ff. 
spatial  phenomena  of,  i, 
stimuli  for,  103. 
temporal  phenomena  of 
Helmholtz  theory  of,  i3« 
Hering  theory  of,  140  ff . 

Visual  purple,  115. 

Vowel  qualities,  156  ff. 

Weber's  Law,  209-215. 
White  matter  of  nervous  s: 
Will,  522  ff. 
Wundt's  figure,  312. 

Yellow  spot,  114. 
Zollner's  illusion,  312. 


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